the Eastern Orthodox Church and the Roman Catholic Church
It is when The Roman Catholic Church and The Eastern Orthodox Church had The Great Schism, in which The Roman Catholic Church broke off The Orthodox Church.
Roman Catholic AnswerThe Catholic Church is sometimes known as the Western Church to distinguish it from the Eastern Orthodox Church.
the Eastern Orthodox Church
There were two main churches: Roman Catholic and Orthodox. - UPDATE - Actually there were three main churches at the time, the Roman Catholic Church, Eastern Orthodox Church and Oriental Orthodox Church. The Oriental Orthodox Church was the first church to break away from the Orthodox Church (Eastern Orthodox Church) in 451AD followed by the Roman Catholic Church in 1054AD.
No, it is not in communion with the Catholic Church.
No, the Pope is the head of the Roman Catholic church. The Ecumenical Patriarch is the head of the Eastern Orthodox Church.
Rome.
The Literal Presence Of Christ in the Blessed Sacrament.
No, Orthodox churches are where persons of Greek or Russian Orthodox faith worship. Like the Church of England, the Orthodox also separated from the Roman Catholic Church on matters of doctrine.
Yes. In fact, if a Roman Catholic is unable to partake of the Eucharist in a Roman Catholic church, they may do so in an Orthodox one. The RCC considers Orthodox sacraments valid (including their ordinations to the priesthood).
The catholic church is sometimes considered the collection of churches that developed out of the Great Schism (namely, the Roman Catholic Church and the Eastern Orthodox Church). Although I have never heard someone use the term "catholic orthodox church," I would consider it to be referring to the Eastern Orthodox Christian religion.