Is that why there are small differences in the canon of Scripture?
Mark, the Russian canon is slightly different form other Orthodox canons. The Orthodox Holy Tradition (life in the Church) is different for the Catholic Sacred Tradition in that the latter sees the Tradition alongside the Scriptures (T + S = ST), and the former sees the Scriputres as part of the Holy Tradition, and not separate form it.
What's on the altar are thew Gospels. That's the New Testament or Covenant of God in his own words. That's the core. The rest is secondary or deuterocanonical, and is interpreted through the Gospels, including the Old Testament.
Whoever professes the same faith as stated in the Nicene Creed (sans filioque) and maintians the life in the Church through the Eucharistic liturgy of the Church, regardless of their canon. No Ecumenical Council has ever established the Church canon, and Trent is not recognized as Ecumenical by the East.