History of the Russian Orthodox Church
While St. Andrew the Apostle is supposed to be the founder of Russian orthodox, the Orthodox when Prince Vladimir chose Christianity to be the state religion of what would become Russia. Christianity was chosen by Vladimir after listening to the various arguments that were against Judaism and Islam which required and the patient of alcohol and the consumption of pork. Prince Vladimir was impressed by the clergy churches in Constantinople in what is now Istanbul, Turkiye was the seat of the Byzantine Empire which came about following the fall of the Roman Empire (well at least the west side as the Byzantine Empire was Part of the Eastern side of the Roman Empire). This came about 66 years before the schism in Christianity which saw Eastern Orthodox and Roman Catholicism split but co-exist under the same religion. The branch of Christianity that would become the Russian Orthodox Church was in Kyiv in modern day Ukraine what but in the 14th century, this seat moved to Moscow. Of course as the Russian Orthodox is Russian they do not call Kyiv, Kyiv and instead they call it Kiev. December 1448 is considered the birth of the modern Russian Orthodox church as this was when a Russian Bishop named Jonas been installed as the metropolitan of Kiev and all Russia. The Russian Orthodox Church was the church of Russia was even before Russia was called Russia!
While Western Europe was emerging from the Middle Ages and embracing the Renaissance and reformation, Russia remained isolated from the west (like what it is now) and the Russian orthodoxy was kept untouched by the changes in spiritual and intellectual life that has been felt elsewhere. Russian orthodox was pivotal for the survival and the life of the young Russian state and such holy figures such as third years of Adonis and Metropolitan what about the Russian Orthodox Church during and spiritually and economically. The church was only recognized during the reign of Tsar Fyodor I and his brother-in-law Boris Godunov when the Moscow patriarchate was established. The religion underwent many changes and reforms during the years being changed, downsized and enlarged depending on what was going on in Russia at the time. Of course as Russia expanded so the Russian Orthodox Church, during which so many parishes been established within Russia's new land claims. There was also a religious Renaissance within Russian Orthodoxy which came about just a few short years before the start of the Russian Revolution when the Revolution came and went bringing in the Soviet Union, many churches were closed down due to the Soviet bias against religions.
However the church survived the Soviet years thanks to migration to various other countries like America so when the Soviet Union collapsed the Russian orthodox special programs aired in 1992 to help their new followers on how to practice Russian orthodoxy.
Why are the Catholic church of the Pope as the head of the church, Russian orthodox churches have Jesus Christ as their head of church and they also have different dates for feasts, the most notable example is that they have Christmas on the 6th of January which is the Feast of the Epiphany within the Catholic Church. In the last 30 years and Ukrainian branch of the Orthodox Church was founded which recently made their Christmas date 25th December like Catholism and Protestantism.