difference between origins and awakening?

[WD40]

What is the difference between dragon age origins and dragon age origins: awakening?
Awakening is a different game or expansion pack?

[AxeKnight]

Awakenings is an expansion set directly after the events of origins, you can even continue with the same character or make a new one, though it changes the back story a little.

[K00lex]

Awakening's additions:
- increase level cap to 35 (new characters starts at 18; imported Wardens at savegame used)
- can get 3 or even 4 specializations (based on level gained)
- 6 new specializations (2 per class)
- new companions (but no romance option)
- new locations and monsters
- new talents & spells
- runecrafting
- armor runes
- 2 new material tiers
- new unique/powerful items
- new achievements/trophies
- can respec your Warden or companions (attributes, specializations, & talents/spells) anytime via a tome (sold by Merchant Herren, unlimited availability)
- most DLC items won't import, except Return to Ostagar