Prole

Catholics: follow the pope as Christ on earth and believe him to be infallible as far as the Church is concerned. Weekly Mass on Sundays or Saturday nights. Priests are the ones who give/celebrate the Mass. Priests can't marry, and they take a vow of celibacy. Nuns are like female priests, but they don't give Mass, they just teach and stuff. They take a vow of celibacy and of poverty. The nuns who taught me in Catholic School wore small gold wedding bands because they were "married to Jesus" but I think that varies by the types of nuns.
Catholics pray to Mary (the mother of Jesus) and the saints. Many saints have their own feast days, when Mass will be held in their honor. Certain saints called patron saints also represent different things and praying to different saints is supposed to make different things happen. Saint Joseph is the patron saint of homeowners, and I think if you're trying to sell your house you're supposed to bury a statue of him upside-down in your front yard or something. Saint Jude is the patron saint of lost causes, so old Catholic grannies will pray to him when their adolescent grandchildren screw up. There is a patron saint for EVERYTHING.
Catholic hierarchy is as follows: priest < bishop < archbishop < cardinal < pope. You have to be a priest before you can be a bishop, bishop before archbishop, etc. and there is only one pope. You can have as many priests as you want, but I believe there are x numbers of available spots for everything else.
The big deal for Catholics is the Eucharist/Holy Communion. A priest will take wafers and wine, bless them, and transform them into the body and blood of Christ for the congregation to partake in. Communion is a huge deal. Kids receive it at age 7 (the age of reason, because you need to be able to know right from wrong and have a good soul and stuff) and the boys wear little suits and girls wear little white dresses and veils. Lots of parents throw parties for this. It's not as big as a Jewish Bar/Bat Mizvah, but as far as Catholics go it's comparable. And some people think the whole Communion thing is cannibalism, because it's truly supposed to represent and BE the body and blood of Jesus.
There are 6 other sacraments besides Eucharist/Communion. Baptism comes first (along with Confirmation for Byzantines), then Reconciliation/Penance (confession), then Eucharist/Communion, then Confirmation. You're confirmed around age 12 and it's the gift of the Holy Spirit. The Bishop confirms you by putting oil on your forehead and letting you "receive the holy spirit", and you also pick another name to call yourself/for the Holy Spirit to call you. So that's cool because you get another name, hah. Then some Catholics have other sacraments: Marriage, Holy Orders (becoming a priest or a nun, obviously not applicable to everyone), and Last Rites/Anointing of the Sick if you're seriously ill.
Basically Catholics: leaders need to get laid, pray to a bunch of people/beings other than God, sacraments, possibly cannibals.