Answer:
The Russian Orthodox Church is in communion with other Eastern Orthodox Churches, and with the Patriarch of Constantinople (the city whose name was changed to Istanbul inthe 1920s). The Greek Catholic Church (which is maybe what you mean by 'Catholic Orthodox') have the same liturgy as the Russian and other Eastern Orthodox Churches. But they are in communion with the Pope of Rome and thus part of the Roman Catholic Church. There are, for instance, quite a lot of Greek Catholics in the Ukraine.
The Orthodox cross is different than the Christian cross. The reason being is that the Orthodox cross has another strike. Also their main holidays are also different.
First of all, there is no such thing as Greek Catholic to my knowledge. There are Greek Orthodox and other Eastern ORthodox as you mentioned including the Russian ORthodox but they are no way ion communion for the Pope of Rome. The Pope means nothing to the Orthodox and are strictly in communion with the Roman Catholics ONLY. You may be thinking of the Byzantine Catholics and the only relationship they to the Orthodox is the Byzantine Cross. And the Byzantine cross is not different from the Christian cross - It is a Christian cross. However, you are right that the cross looks different. It is a typical cross, but with 2 extra crosses, one on top for the sign, and one the bottom which is tilted so that it one end is up towards the right and the other end tilting to the ground. There are alot of Ukrainian Catholics yes. Main holidays are only different by date. Jan. 7 is Xmas and Easter is generally around Passover, only due to the fact that they follow the Julian calendar (from ancient apostolic times) as opposed to following the Roman calendar. All Liturgy's are basically the same in practice, but they do differ s
lightly.