They are shall we say about 85% in synch with each other. Russian and Greek Orthodoxy worship the same God, honor the same ( generally) saints, and have an elaborate system of rituals and sacraments- numbering 7 major sacraments. The ORTHO Rites differ in the following. They do not recognize the primacy or supremacy of the Pope, there is loosely more latitude for such things as divorce. There are differences in worship apart from the obvious language angles- for example the (Three times around the Horn) practice (l080 degrees of arc, By the way) which is a Wedding protocol in Russian and Greek Ortho use but has no counterpart in the Roman Catholic church. Statues are not used in Ortho churches but two-dimensional Icons, also spelled Ikons are. Communion is frequently under both kinds- Bread and wine. Finally one major difference is priests or ministers are permitted to be married- (only once) if a minister"s wife dies he cannot remarry) but Bishops are requiired to be celibate and the higher-ups are only selected, so to speak from the (Regular- celibacy-bound clergy). There are different ecceleasiatical ranks such as Metropolitan- a sort of Urban Bishop-like officer. No Stacy, he does not wear a subway-conductor"s flat-top hat! That"s an old joke, lilke those about De Gaulle and the IRT. Kidding aside the two faiths have a lot in common and stately, formal ritual is a mark of the Orthodox faith, no frivolous folk-hymsn unless handled by the choirs.
No
Eastern Orthodoxy was the primary religion of the Byzantine Empire (330-1453)
Poland is a chiefly Roman Catholic country, which of course does not mean it is the only religion there - there are also many Protestants, Muslims, Jews and the Orthodox, not to mention members of other faiths, but the main religion is Catholicism.
Alexander III
There is no specific ceremony for a Protestant converting to Catholicism, but anyone entering Catholicism must be Baptised.
Orthodoxy, Catholicism, and Protestantism
Christianity. In Latvia, Lutheranism, Catholicism and Orthodoxy. In Estonia, Lutheranism and Orthodoxy
Christianity split into Catholicism & Orthodoxy.
No
Russian Orthodoxy is not part of the Catholic religion. I don't know the exact time or history, but Catholicism came about once it broke away from Orthodoxy. Hence, Catholicism is the first religion to break away from Orthodoxy. Historically, Orthodoxy is the first established Christian religion, Catholics upon breaking away, became the 2nd Christian religion.
The main branches of Christianity are Catholicism, Protestantism, and Eastern Orthodoxy. Catholicism recognizes the authority of the Pope and has specific sacraments. Protestantism emphasizes individual interpretation of the Bible and rejects the authority of the Pope. Eastern Orthodoxy has a different hierarchy and liturgical practices compared to Catholicism and Protestantism.
Islam   45% Serb Orthodoxy   36% Roman Catholicism   15% Others   1%
Saint Joseph is celebrated to one extent or another all over the world. He is venerated in Catholicism, Anglicanism, Lutheranism, Eastern Orthodoxy, Oriental Orthodoxy.
Eastern Orthodoxy is one form of Christianity. Some more may be Roman Catholicism or Protestantism.
Catholicism. They make up their own rules as they go along.
W. A. Visser 'T Hooft has written: 'Anglo-Catholicism and orthodoxy'
I assume you mean the official split into Eastern Orthodoxy and Roman Catholicism, which happened in 1054.