No there is a difference, a major difference. If the Pope were infallible in himself, then he could go around, willy nilly, proclaiming everything he wanted to as dogma. In fact, if the Pope were infallible in himself, he could always accurately predict the outcomes of lotteries. Further, he would not need divine protection for his infallibility. The Catholic doctrine of Papal infallibility safeguards tradition. The ugly characiture is a heretical monstrosity.
.......... (Q) Must not Catholics believe the Pope in himself to be infallible? Nice try Father Ambrose, but not even ultramontanists believe that Pope in himself is infallible. It would be heresy to declare so.
.......... (A) This is a Protestant invention: it is no article of the Catholic faith.
In fact Pastor Aeternus excludes the possibility of the Pope being in himself infallible:
"We teach and define that it is a dogma Divinely revealed that the Roman pontiff when he speaks ex cathedra, that is when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme Apostolic authority, he defines a doctrine regarding faith or morals to be held by the universal Church, by the Divine assistance promised to him in Blessed Peter, is possessed of that infallibility." - Pastor Aeternus
Notice the infallibility is not derived from the Pope himself, but is rather the result of his Apostolic authority, when he speaks ex cathedra, and by virtue the Divine assistance promised to him in Blessed Peter. This is a far cry from the Pope being infallible in himself. Thus the catechism that you site is accurate and in harmony with the dogma of Papal Infallibility.
This is a difference without meaning. If Father Ambrose claims that the Pope by himself is infallible, he is saying the same thing as Pastor Aeternus. After all, the Pope is the "Supreme Pontiff and the Vicar of Christ." We are not talking about the Bishop of Pittsburgh or the Archbishop of Napoli here. We are talking about the super special charisma that is bestowed upon the Bishop of Rome, making him able to be infallible when, blah, blah, blah.. Come on now Papist, quit splitting hairs here and admit the obvious. Pace and out.
Of course it is indeed a heretical position. That is what we see when we read the dogma stated as "We teach and define that it is a dogma Divinely revealed that the Roman pontiff when he speaks ex cathedra, that is when in discharge of the office of pastor and doctor of all Christians, by virtue of his supreme Apostolic authority, he defines a doctrine regarding faith or morals to be held by the universal Church, by the Divine assistance promised to him in Blessed Peter, is possessed of that infallibility." - Pastor Aeternus
It is precisely because he is the Roman Pontiff that he can speak ex cathedra. Notice that this definition does not say that the Pope is infallible when he enunciates a doctrine that all have believed from the Apostles on; it says "he defines a doctrine regarding faith or morals to be held by the universal church." I do not care is he does it many times, once or at no time. It is this "heretical monstrosity" as you call it that is at issue. Y'all have defined the Bishop of Rome to have special authority above any other bishop; y'all have declared him to have universal jurisdiction contra anything in the Holy Scriptures, the Seven Ecumenical Councils, the Fathers; indeed, the Holy Tradition that we all adhered to over 7-8 centuries (at least); y'all have come up with this illogical "authority" of being somehow infallible as if the Bishop of Rome is not mortal. What next, will you declare him to be sinless? Because you do in fact say that when he speaks ex cathedra (that is as the Bishop of Rome).
You really ought to hear some of us when we read things like this and say to you that these assertions make no sense in terms of the reality and meaning of the doctrine.
You are in error in your understanding.
I know that is tough to believe because you are so deeply convinced that you cannot be.
But as a Catholic who does know a little bit about the meaning of Catholic doctrine, I am telling you that you are out in left field with this paragraph. You certainly may stay there. I hope not all Orthodox believers decide to stay with you, but one never knows.
If you want to know how crazy it all is pick up ANY Orthodox text and in it you will find something about how Orthodoxy is not like the Catholic Church in this or that...always a comparison of some kind, and very often not recognizable to Catholics as Catholic teaching.
You NEVER find that in Catholic theology and spiritual texts unless there is some explicit intent to discuss the eastern confessions. It says something when it becomes clear that the Catholic never needs to identify him or herself by comparison with Orthodoxy.
For most of them you don't exist except as an oddity...and so you are going to stand here and tell me that you know better than the rest of us what we believe, or can tell us the meaning of texts better than our own pastors and teachers?
I don't think so.
Dear Mary--You seem to be going off on a tangent here. Let's get back on track. In a subsequent post, you referred to the First Vatican Council. Thank you for the link. It has the usual whereas's and then comes the dogma on Papal Infallibility. One or two of the whereas's caught my eye. It says:
"1. That apostolic primacy which the Roman pontiff possesses as successor of Peter, the prince of the apostles, includes also the supreme power of teaching.
* This holy see has always maintained this,
* the constant custom of the church demonstrates it, and
* the ecumenical councils, particularly those in which East and West met in the union of faith and charity, have declared it.
2. So the fathers of the fourth council of Constantinople, following the footsteps of their predecessors, published this solemn profession of faith:
* The first condition of salvation is to maintain the rule of the true faith. And since that saying of our lord Jesus Christ, You are Peter, and upon this rock I will build my church  , cannot fail of its effect, the words spoken are confirmed by their consequences. For in the apostolic see the catholic religion has always been preserved unblemished, and sacred doctrine been held in honour. Since it is our earnest desire to be in no way separated from this faith and doctrine, we hope that we may deserve to remain in that one communion which the apostolic see preaches, for in it is the whole and true strength of the christian religion  .
What is more, with the approval of the second council of Lyons, the Greeks made the following profession:
* "The holy Roman church possesses the supreme and full primacy and principality over the whole catholic church. She truly and humbly acknowledges that she received this from the Lord himself in blessed Peter, the prince and chief of the apostles, whose successor the Roman pontiff is, together with the fullness of power. And since before all others she has the duty of defending the truth of the faith, so if any questions arise concerning the faith, it is by her judgment that they must be settled." 
Then there is the definition of the council of Florence:
* "The Roman pontiff is the true vicar of Christ, the head of the whole church and the father and teacher of all Christians; and to him was committed in blessed Peter, by our lord Jesus Christ, the full power of tending, ruling and governing the whole church."  "
OK now, would you agree that claims are not the same as factual statements? I mean that this passage claims that ecumenical councils have declared the super-bishop character of the Papacy (I am obviously paraphrasing). Yet when it gives the three examples, we find that they are not objectively true ecumenical councils, let alone one of the first seven. Here is what the Wiki says (please correct my source if it is wrong, but I would appreciate hearing the why instead tautologies). (I have also bolded the relevant sections)Fourth Council of Constantinople
: "The Fourth Council of Constantinople (Roman Catholic) was the 8th Catholic Ecumenical Council held in Constantinople from October 5, 869 to February 28, 870. It included 102 bishops, 3 papal legates, and 4 patriarchs. The Council met in 10 sessions from October 869 to February 870 and issued 27 canons.
The council was called by Emperor Basil I the Macedonian and Pope Adrian II. It deposed Photios, a layman who had been appointed as Patriarch of Constantinople, and reinstated his predecessor Ignatius.
The Council also reaffirmed the decisions of the Second Council of Nicaea in support of icons and holy images and required the image of Christ to have veneration equal with that of the gospel book.
A later council, the Greek Fourth Council of Constantinople, was held after Photios had been reinstated on order of the Emperor. Today, the Roman Catholic Church recognizes the council in 869–870 as "Constantinople IV", while the Eastern Orthodox Churches recognize the councils in 879–880 as "Constantinople IV" and revere Photios as a saint. At the time that these councils were being held, this division was not yet clear. These two councils represent a break between East and West. The previous seven ecumenical councils are recognized as ecumenical and authoritative by both Greek-literate Eastern Christians and Latin-literate Western Christians. This division led eventually to the East-West Schism of 1054."The second council of Lyons
: "Wishing to end the Great Schism that divided the Eastern Orthodox churches from the Catholic Church, Gregory X had sent an embassy to Michael VIII Palaeologus, who had reconquered Constantinople, putting an end to the remnants of the Latin Empire in the East, and he asked Latin despots in the East to curb their ambitions. Eastern dignitaries arrived at Lyon on 24 June presenting a letter from the Emperor. On 29 June (the Feast of Peter and Paul, patronal feast of the popes), Gregory celebrated a Mass in St John's Church, where both sides took part. The Greeks read the Nicene Creed, with the Western addition of the Filioque clause sung three times. The council was seemingly a success, but did not provide a lasting solution to the schism; the Emperor was anxious to heal the schism, but the Eastern clergy proved to be obstinate. Patriarch Joseph of Constantinople abdicated, and was replaced by John Bekkos, a convert to the cause of union. In spite of a sustained campaign by Bekkos to defend the union intellectually, and vigorous and brutal repression of opponents by Michael, the vast majority of Byzantine Christians remained implacably opposed to union with the Latin "heretics". Michael's death in December 1282 put an end to the union of Lyons. His son and successor Andronicus II repudiated the union, and Bekkos was forced to abdicate, being eventually exiled and imprisoned until his death in 1297. He is to this day reviled by many in the Eastern Church as a traitor to Orthodoxy.
The Council of Florence: "The Council transferred to Ferrara in 1438 and to Florence in 1439 had meanwhile successfully negotiated reunification with several Eastern Churches, reaching agreements on such matters as papal primacy, purgatory, and the word "Filioque" added in the West to the Nicene Creed. The most important of these unions, that with the Eastern Orthodox Church, though accepted by all but one of the Greek bishops at the Council, was rejected by popular sentiment and came to a complete end with the fall of Constantinople in 1453.
The Council also declared the Basel group heretics and excommunicated them; and the superiority of the Pope over the Councils was affirmed in the bull Etsi non dubitemus of 20 April 1441."
So, what we see here is a specious claim by the First Vatican Council regarding the ecumenicity of these councils that were not acknowledged to be ecumenical by the Orthodox Churches at the time of the First Vatican Council. The premises are evidently wrong, therefore the conclusion must be false. This whole Papal supremacy and infallibility turns out to be nothing but the doings of a part of the Church (I am being very liberal here and risk being a proponent of the branch theory), a matter of power politics, self-aggrandizement and a mockery of Christ teaching that the first will be last while the last will be first.