Mike, it is a western tendency to underestimate the differences. Also, there are historical reasons why the Orthodox Church doesn't believe in the filioque, purgatory, the Immaculate conception etc. . . but they're all the same reason. Those elements were added after separation from the West. 

We also overlook the significance of the small things at our peril. For example, the Orthodox Church has no official catechism--not because nobody bothered putting it together but because we don't believe the truth, which continues to be revealed, can be reduced to a systematic formula. How about one Roman Catholic pope's decision to usurp the conscience of the Church by shutting down all discussion of women priests? In the Orthodox Church you can talk about such things freely, as at least two rather well-known Metropolitans and several theologians have, without fear of censure. Conscience and freedom of inquiry are incredibly important. 

Just a couple of examples.