LivLuv...,
Those Church orders refer to monastic life, like ie. the Jesuits (seen as the order which integrated education and religion), the Franciscans (they live very simple lives), the Dominicans, etc. Both priests and nuns belong to different orders, but those orders determine the organization of their personal lives and also the sorts of social issues that the particular order really focusses on. The Church is still the same, the mass is the same, the sacraments are the same and the dogma is the same, even if the priests' background is different. Does that make sense?
But for example, if you look at Baptists, they are not all the same, because there isn't that hierarchy of priest/bishop/cardinal/Pope, so that in a city it is possible to have the 1st Baptist Church and the 2nd Baptist Church and have those two not be affiliated with one another. I agree with you that the splintering may be inconsequential in some places. Also, while the unified nature of the Roman Catholic Church looks good on paper, it's also an illusion of sorts because North American Catholics are very different from the ones in say, Latin America. In general, very leftist Catholics have been branded "cafeteria Catholics" meaning that they pick and choose what they like about the Church's teachings and ignore the rest (ie. abortion/birth control/homosexuality). So you have a united church and people who follow their own creed, but they haven't really splintered in the traditional sense.
I think in today's global world, we'll see even more splitting off, not unification. I guess it's the name of the game.