To add a remark of my own:
Generally speaking, Eastern Catholics all agree that the Pope of Rome is not in heresy. (If they believed he was in heresy, presumably they would break off communion with him.)
With that in mind, if you ask ECs about a difference between Latin and EC theology (e.g. concerning "purgatory") the answer will generally take one of the following forms:
1. There's no essential difference in what we believe, only in the language we use and the emphasis.
2. The Latins are wrong about such-and-such, but the error can't be called a heresy.
Anthony's answers, from what I've seen, pretty much fall under #1.