amok: The definition of DLC is DownLoadable Content - "additional content for a video game distributed through the Internet by the game's official publisher or other third party content producers. Downloadable content can be of several types, ranging from aesthetic outfit changes to a new, extensive storyline, similar to an expansion pack. As such, DLC may add new game modes, objects, levels, challenges or other features to a complete an already released game." (WIkipedia :))
no citation, this definition was invented by an anonymous wiki editor. (I checked the history, he was anonymous)
Tarm: Well that's the problem. The difference between an expansion, which I believe those you mentioned are and a DLC is practically none. After all DLC stands for Down Loadable Content. It can be practically anything.
Edit: Ninjad. :/
Ah, but terms do have colloquial meaning that are different than what the individual words imply.
A roleplaying game does NOT mean "A FPS where you role play a space marine fighting some aliens, has no levelup schema" even though you are playing a role in such a game, it is clearly not an RPG but an FPS.
If it merely meant downloadable content then every single video game, movie, and song ever made is a DLC, because all of them are content you can download
You can't find a video game for the PC today that isn't sold as a download only option. Those have the term "Digital Download Distribution" according to online stores I have been too.
The difference between "Digital Download Distribution" and "DownLoadable Content" might be entirely arbitrary but it exists