Chistians All

I've always been taught in my (Catholic) school that all Catholics are Christians (since we all believe in Christ) but not all Christians are Catholics. There are various sects, the Baptists, Methodists, Mormons, Jehovah's Witnesses etc., just to name a few. These are basically "Protestants", meaning those who protested against policies of the Catholic Church way back in history. What makes us different and what makes us the same? I think a conversation in the Christian Chat Rooms should be interesting.