What is the difference between the Presbyterian Church and the Catholic Church?
The Presbyterian church grew out of the reformation, when corruption in Catholic church leadership made people question the Church. Presbyterian comes from the Greek word for "ruling elder". The Presbyterian shares many of the beliefs of the Catholic church, but instead of being ruled by clergy on up to a pope, the Presbyterian church is ruled by representatives chosen from the laity and clergy of each congregation at the presbytery level. Representatives from each presbytery are then chosen to represent them at the synod level, and representatives of each synod are chosen to make decisions at the General Assembly of the church. The checks and balances and representative governance served as part of the inspiration of the U.S. Constitution.
So that is how we are run. As for what we believe, it is remarkably similar to the Catholic church, in my opinion.
At Communion (which is typically celebrated once a month instead of every week), the belief of what is going on is a little different from the Catholic view. Catholics believe in transubstantiation, where the bread and wine literally become the body of blood of Christ in a metaphysical sense.
Presbyterians believe that the bread and wine represent the body and blood of Jesus. From my own viewpoint, this makes more sense because when Jesus pronounced, "This is my blood, this is my body," he was was there with the apostles. I doubt they took his words in a literal sense but rather saw his words as metaphoric.
As for joining the church, Presbyterians practice infant baptism like the Catholic church does, although again it is seen to be more symbolic in nature than in the Catholic church. There is a reverent belief that the Holy Spirit is present, but the actual act of baptism is not meant to be an invocation or command of the Holy Spirit, rather a reflection of the recognition of the presence of the Spirit.
Confirmation occurs primarily among teenagers, but is not as structured as it is in the Catholic church. In our church, confirmation classes are offered every year, and any youth who feels accountable for their own faith may attend the classes and be confirmed. Confirmation itself is really the act of joining the congregation as an adult. Confirmed youths can technically serve as deacons and elders (lay leadership positions), although this is rare.
The Presbyterian Communion was formed by those who left the Church that Christ founded, the Catholic Church, 15 centuries after Our Blessed Lord left the earth, as they couldn't live with its beliefs, and formed their own Church using their own version of the Sacred Scripture which they took from the Church and after editing and throwing out the books they didn't agree with, they based their new found religion on their new Bible.