Well, only Rogues can disarm traps, pick locks, stealth, and backstab.
Only Warriors can tank (threat building abilities, use of sheilds, and effective use of heavy armor are limited to warriors), use 2 handed weapons (effectively at least, a Rogue with enough strength could probably equip one, but they'd be gimpy)
Mages - well they cast spells.
Skill access is the same for all classes (provided they meet attribute requirements), and everyone can equip all kinds of armor provided they meet the requirements. But I like that. The restrictions tend to come in more subtle forms than something like 'rogues can't wear heavy armor' - it's more like rogues can wear heavy armor, it's stupid, but you can do it.
Rogues and Warriors are more similar than Mages are to anything, but they're still quite distinct. That said, a DPS dual wield rogue and a DPS dual wield warrior are more similar than a tanking warrior is to a DPS warrior.
As for talents, rogues and warriors have dual wield and archery talents in common, but apart from that all talents/spells are class exclusive.