So far off the top of my head:
Equipment
-Crossbows (DG - crafting only)
-Dwarven Crossbow (DG only)
-Fire/Ice/Shock Enchanted bolts (DG only)
-Dawnguard armor (heavy & light) (either questline)
-New Heavy Falmer Armor
-Dawnguard Weapons & Unique Shield (either)
-New restoration/conjuration spells
-Dragonbone Weapons
-Shellbug Helm
-Unique Vampire armor (either)
-Auriel's Bow
-Auriel's Shield
-Blood Potions/Human cattle (Vampire only)
Abilities/Content
-Bolt crafting (DG only)
-Arrow crafting (all)
-Vampire Lord form (Either questline)
-Vampire Lord perk tree
-Werewolf perk tree
-New Vampire looks (eyes and lips)
That's all I can think of off the top of my head, any help guys?