Your reply about the big difference being what colour robes to wear on a certain was actually pretty close. It's not quite that simple, of course, but you're right that the distinction is practice, not belief.
All the Churches in communion with Rome believe exactly the same things. They all believe the Pope is the infallible head of the Church, that Jesus is truly present in the Eucharist through transubstantiation, that baptism removes original sin, that women cannot be ordained, that Mary remained a virgin, was without sin, and was assumed body and soul into heaven, and all the other Catholic beliefs.
In the Western Church, there are several rites. The main one is the Roman Rite, celebrated according to the 1970 Missal. By permission, the 1962 rite can be used, and some Catholics choose to worship in this style. The Anglican use is the Anglican liturgy from the Book of Common Prayer, slightly modified to bring it in line with Catholic teaching. A few Anglican congregations who wanted to all convert to Catholicism have been allowed to use this. The Ambrosian Rite is used only in the Diocese of Milan and the Mozarabic is used in a few places in Spain.
Catholics attending any of these Rites believe exactly the same things, but may express them differently. Anyone who does not believe what the Church teaches is no longer Catholic.
