Johnathanamz: Expansion Packs add a lot of new stuff DownLoadable Content (DLC) adds only like 5 maps or 1 new gun skin or 1 new clothing skin or 10 new quests or 10 new vehicles, Stuff like that is DLC's.
HijacK: Downloadable Content is content that is downloaded. The size of it is irrelevant. Expansion Packs are nowadays downloadable, but you seem to forget they were in physical form even a few years ago, like Dragon Age: Awakening.
As long as they are downloadable, they are considered DLC.
I disagree slightly. The size of it is relevant, I believe this is why historical expansions were able to be sold retail in the first place. As you have mentioned, dragonage:awakening is a good example of this. To throw another one in, so is the first call of duty expansion, united offensive.
Expansions do offer (or used to offer) a great deal of extra gameplay, measurable in hours compared to rubbish DLC that is quite often not worth the money, short and unnecessary and latterly obviously removed from the original release and then milked.
United offensive as an expansion has 16 hours of extra gameplay and that is a damn site more than you will get from most DLC nowadays and is quite spectacular when you consider that the most recent call of duty games (sold as full versions) amount to a fraction of this gameplay time (6-9 hrs these days I believe?)
So yeah, basically there is a serious distinction to be made between expansion and DLC even though both can these days be downloaded. Expansions are becoming rare beasts.