Discuss the characteristics that distinguish and separate the celtic christian church from the roman christian church?

Many of the differences have to do with the festivities they celebrate, for example the Easter which they celebrate in different ocassions due to the fact that they have different methods to calculate festivities. We can say that the main reason for differences is related to the historical event called  the Council of Nice. Before it, both churches were close but after this council, the Celtic church saw alterations that were not good at all and they considered they could not support the "improvements" the Roman church did. Another point is the baptism in which one says that there should be a total immersion of the body and the other says that is better only to sprinkle water. 

It covered the territory of land across eurasia from northeastern europe to the pacific ocean.

The answer is protestant reformation.