To further the confusion, Dark Elves originally were nearly the same as the high elves (IMO), until they gained the assassin. I personally like to look at how all 4 elves differ:
High Elves: They have a great blitzer and a super fast receiver that has better armor and strength than most receivers. They can play like the humans except that they are faster and more agile.
Wood Elves: They play a pure passing game. Essentially, they pass and make touchdowns every time they gain possession of the ball. The treeman and wardancer are their unique players. Regardless, everyone of them (except for the treeman) is very fragile and expensive.
Dark Elves: These guys were nearly the same as the high elves. The dark elf blitzer was essentially the same as the high elf equivalent and the witch elf was the only player that was different from the high elf receiver (lion warrior). Recently, they changed greatly with a runner and assassin player. However they have no one who specializes as a ball thrower. I find them to be a really interesting brawling team that doesn't quite play the passing game like the wood elves or high elves.
Pro Elves: I don't really know WHY they were ever created. They have the same, weak armor issues of the wood elves, and the speed problems of standard dark and high elves, Sure, I like their catchers better than the High Elves, but I prefer the high elf blitzers over the Pro Elf version.
Whew! So, how do they differ when we move into the Team Manager versions? Well, the High Elves would be sort of another human team. The Dark Elves would probably be some sort of cheating team like Chaos. The Pro Elves would probably best resemble the Wood Elves without the Treeman and a human blitzer instead of the wardancer. Ick! I don't like thinking about how the shades of elf convert from the mini game to this game. The 4 prong specializations of "cheat", "ball handling", "blitz", and cycling your players is quite a different way to sort them. Without some sort of NEW mechanics like an undead/nurgle resurrection, I cannot see how these many new teams would play differently than the existing ones.