Amongst other things:
- Races grant benefits at levels 1-10 like paragon paths and epic destinies, and racial feats make an elf fighter and a dwarf fighter play very differently (Races and Classes, web previews)
- Wizard and fighter powers heavily dependant on weapon/implement and secondary stats, making the orb/staff wizard and the sword/axe fighter as different to play as a melee/blaster cleric or a fey/infernal warlock (Races and Classes, leftover PHB fluff, web previews)
- Grouping at-wills, encounters and dailies by class - paladin encounter=smite, cleric encounter=battle prayer, warlock daily=invocation, wizard encouter=power word etc. (Races and Classes)
- Paragon paths built for multiple classes (Races and Classes)
- Skill challenges styled after combat (leftover PHB fluff, web previews)
- Monsters with less HP grind, especially elites and solos (Against the Giants and Dungeons of Dread RPG cards)
- Monsters with effects that takes special actions to end and lasting effects even after combat has ended, like the Shadow Demon, Shade Knight, Warrior Wight and Bralani (Against the Giants and Dungeons of Dread RPG cards)