Orthodox Church is a branch of Christianity. 1, the history is different. At first, there was only one church in Christ. 1054, the eastern and western churches split. Western churches centered on Rome call themselves "Catholicism", while Eastern churches centered on Constantinople call themselves "Orthodox Church" or Orthodox Church. /kloc-In the 6th century, the Reformation took place in Western Europe and Northern Europe, and the Reformed Church was separated from Catholicism and collectively called Protestantism. 2. There are different forms of churches. Catholicism still retains a unified church, calling itself "the most sacred, open and handed down by the first apostle", and the Vatican is the center of Catholicism in the world. The Orthodox Church originally had a unified church centered on Justinian. With the demise of the Eastern Roman Empire, churches in various countries were not unified, but Constantine, the patriarch of Istanbul, retained the title of "ecumenical patriarch" today.

3. Different religious languages. Catholicism uses Latin as its religious language, but now it also allows all localities to pray in national languages. The Orthodox Church originally used Greek as its religious language, but now there is no unified Orthodox Church, so it generally uses national languages.

4. Different requirements for clergy. Catholic clergy are not allowed to get married. The Orthodox Church used to be like this, but now it is not strict.

5. The titles of clergy are different. Catholicism is Pope, Cardinal, bishop and priest. Orthodox Church is patriarch and priest.