We follow the Nicene Creed, which strictly affirms our beliefs and rejects claims that would run contrary to the following articles:

I believe in one God, the Father Almighty, Maker of Heaven and earth, and of all things visible and invisible.

And in one Lord Jesus Christ, the Son of God, the Only-begotten, begotten of the Father before all ages; Light of Light: true God of true God; begotten, not made; of one essence with the Father, by Whom all things were made;

Who for us men, and for our salvation, came down from the heavens, and was incarnate of the Holy Spirit and the Virgin Mary, and became man;

And was crucified for us under Pontius Pilate, and suffered, and was buried;

And arose again on the third day according to the Scriptures;

And ascended into the heavens, and sitteth at the right hand of the Father;

And shall come again, with glory, to judge both the living and the dead; Whose kingdom shall have no end.

And in the Holy Spirit, the Lord, the Giver of Life; Who proceedeth from the Father; Who with the Father and the Son together is worshipped and glorified; Who spake by the prophets.

In One, Holy, Catholic, and Apostolic Church.

I confess one baptism for the remission of sins.

I look for the resurrection of the dead, And the life of the age to come. Amen.

Like the Catholic and Oriental Orthodox Churches, and like the Church of the East, we believe in sacred tradition and consider the Bible to be a product, and part of, tradition. So we reject the concept of Sola Scriptura, we reject that faith and works cannot be separated, we pray to the saints, we hold the Theotokos (Mother of God, Most-Blessed Virgin Mary) in high esteem, we keep some doctrine that isn't contained in scripture such as the Dormition, and so on.

While Western Christianity took more interest in philosophy and explanation, Eastern Christianity took more interest in asceticism and mystery, and this is reflected in Eastern Orthodoxy too. Also, administratively, we are different from the Catholics: they have the Pope as the supreme authority of the Church, to the point he can declare dogma ex cathedra. Meanwhile, each "segment" of the Church is autocephalous, as opposed to different Catholic Churches, which are autonomous. This means that each Orthodox Church does not respond to higher authority. Historically, the Orthodox perspective is that the Church as a whole has, at its head, a Pentarchy: the Sees of Rome, Constantinople, Alexandria, Antioch and Jerusalem, with Rome enjoying the honorable title of "first among equals" and being able to arbiter on issues within the Church. This title has been passed on to the See of Constantinople after Rome broke away, so you might say our "Pope" is the Eucumenical Patriarch, the Patriarch of Constantinople.

Historically, we had a fight with the Roman Catholic Church for several reasons (addition of the "filioque" to the Nicene Creed, Western tradition getting too out of line with the rest of the Church, etc) but it basically comes down to what exactly is the authority of the Pope of Rome: is it a position of primacy (the Pope is honored as the successor of Peter and is sought after when the Church needs an arbiter on disputes) or a position of supremacy (the Pope is the Vicar of Christ and the head of the physical Church, and has authority over other jurisdictions of the Church)? We each picked our interpretation and walked away from each other. 1054 is the date used for the proper schism, but really it wasn't a clear cut and there were tensions since at least the 9th century.