What's the difference between a Roman Catholic and a Christian?

i'm not entirely sure, as far as i know they read the same book, celebrate the same holidays and such, but as a lad i went to a roman catholic school, they didn't tend to enjoy being called christian, but i've never really gotten the catholic, protestant and christian difference myself, it seems that it is and isn't when it suits the masses. and for some reason,every Abrahamic religion loves the pope, unless some priests do some "less tharighteousus" things, then its kind of off topic for a while, until the P.R is properly managed again at least.