Fighters are significantly more diverse. The game is really going in the direction of play whatever class you want however you like. Fighters get a good amount of diversity. We only have the first ten levels to go on. (There are tiers like in the last game, but we haven't heard anything about epic destinies capping the campaign, so maybe we're back to 4e's limitless level?)
As it stands, we've got some different paths to branch out into. Feats aren't nearly as boring and mechanical as they were in 4e. They're almost like powers now, or more interesting, static bonuses, and fighters get some extra ones. But this isn't surprising, every class right now can acquire certain class-specific feats for free.
The current fighter setups we're supposed to focus on are a tank-fighter that is much like the basic 4e one, except a little less "gamey," a warlordesque fighter (a ton of feats support this style of martial badassery), and a man-at-arms fighter that will fuck your shit up, much like the Slayer fighter from Essentials in concept.
Wizards we've been given a bit of leeway with, playtest-wise. We've basically been told, "Okay, here are some spells that a wizard can use, we're not totally sure if we should go for a 3.5 model, a 4e model, or something new yet, so fiddle with this." As a wizard, you're going to be able to choose how versatile you are right now. There are a decent amount of spells, and they scale with level. They're more "different" than in 4e. Encounter stuff is here to stay, though. It seems that ever since the concept appeared in ToB, Wizards will never lose their love of per encounter abilities.
The typical wizard will play with a fair number of encounter spells at this point in time. It's a sort of pick-and-choose from your current spells-per-encounter list. It's not YOU MUST USE EACH OF THESE ONCE. More versatility. It's good.