It's basically better talent trees, not all that different.
For an actual different experience you need mods like Apocalypse (155 new spells) and most importantly the mod that instakills you if try to play a stealth archer.
Nah man, if you want a truly different experience, try out a heavily modded modpack on Wabbajack.
There's one I really enjoyed called Librum for the mage playthrough. Didn't even have any mana to start with and spent like a full playthrough just to get my first spell. Lived in inns for a while a spending day after day to study, doing odd jobs for money. Couldn't even get into the college at first because I didn't know magic.
Granted, very few modpacks actually explain to that extent, but I mean, most packs from my experience actually do briefly explain what it does. At least in my experience. Not totally sure what else you're looking for.
Doesn't take all that long once you figure out less is more. You don't need 16 times the detail in grass textures, just add a few big gameplay changing mods and get going.