Absinthe does not really have an effect different from other kinds of alcohol, though some feel the herbal essences therein may produce a heightened alertness or some other mild effect.
I mostly said that because I liked the cleverness of my phrase. But Absinthe, Chartreuse, and a few other liquors certainly have unique effects on me compared to whiskey, gin, etc. I like absinthe, but anymore, I won't drink anything more than 2 shots worth. It's sneaky. Think about things like wine and champagne. They are a bit different than drinking normal liquor or beer.
No way though is drinking three glasses of Knob Creek equal to drinking three glasses of Chartreuse or Absinthe.