>>711234
Catholicism is centralized around the Church of Rome, which was founded in the 1st century and of whom the bishop (the Pope) is the successor of Peter. The traditional liturgical language is Latin, the traditional Bible that is used is the Vulgate, the liturgy that is principally used is the Paul VI Mass (also called the Novus Ordo). Besides the Church of Rome, there are also 23 (I think?) churches in communion with Rome, called Eastern Catholic Churches (and Melkites are Eastern Catholics). The Catholic Bible canon has 73 books. The Catholic Church recognizes 21 ecumenical councils (authoritative councils held to define the faith and practice of the Church better against heresies).
Eastern Orthodoxy recognizes the Church of Constantinople (the Ecumenical Patriarchate) as having the primacy, but it is not centralized around it. Some chuches were founded in the 1st century (Antioch, Alexandria, Jerusalem notably) and some were not. Liturgical languages are Church Slavonic or Koine Greek but churches aren't forced to adhere to these at all (all Antiochian Orthodox services I've heard were in Arabic for instance). The traditional Bible that is used is simply the Old Testament in Greek (the Septuagint) and the New Testament in Greek. The liturgy that is principally used is the Divine Liturgy of St John Chrysostom. Overall there are 15 autocephalous (self-ruling) Eastern Orthodox Chuches. The Eastern Orthodox Bible canon is 66 books in the Slavonic tradition and 76 books in the Greek tradition. The Eastern Orthodox Church recognizes 7 ecumenical councils.
The Eastern Orthodox and the Catholics had a schism that began in the 11th century and was formally completed in the 15th century, over the following Catholic claims: the Holy Spirit proceeds from the Father and the Son, the Nicene-Constantinopolitan Creed could be modified by the Pope to add this, unleavened bread can be used for the Eucharist, individuals who die without mortal sin but without having done sufficient penance go to a Purgatory before they can enter Heaven, and the Pope is the supreme head of the Church and cannot teach heresy.
This is just for example, but as you can see they are two distinct traditions and they anathematize each other as being heretical.
Similarly, the Oriental Orthodox Church broke off from the Orthodox/Catholic Church in the 5th century because of the Orthodox/Catholic claim that Jesus has two natures, one human and one divine, rather than one human-divine nature. The Church of the East broke off from the Orthodox/Catholic Church in the 5th century because of the Orthodox/Catholic claim that Jesus is not two distinct persons, Jesus the man and Jesus the God, but one person with two natures.
The Protestants broke off from the Catholic Church in the 16th-17th century over a variety of issues. Protestants believe we are saved by faith alone (rather than by faith and works), they reject the supremacy of the Pope, they believe the Bible alone contains the fullness of the Christian religion, they reject Purgatory, they reject prayer to saints, some also reject the use of statues and icons. But Protestantism is such a large thing that I can't cover everything here.