Total War: Warhammer, Difference between story and grand campaign
The Wood Elves and Beastmen DLC came with the faction for the grand campaign but also their own mini-campaign taking place on a small part of the grand map (but a lot more detailed so there are more towns).
For example the Beastmen mini-campaign An Eye for an Eye takes place in the human provinces north of Altdorf, around Midenheim.
The mini campaigns use similar mechanisms to the grand campaign but feature specific characters, subfactions, quests and objectives. The mini campaigns are usually shorter than doing the grand campaign.