Hiding in forests

[Timoleon]

What is the difference of hide_forest and hide_improved_forest attributes?
The units with hide_improved_forest attribute have "Expert at Hiding in Woods" in their description cards.
Has anything to do with a success of an ambush in the campaign map?

P.S: I know that this isn't a EB-specific question, but since this is the only mod I play, I posted it here.

[Cullhwch]

No, it just means that that particular unit needs less foliage than normal in order to hide itself.

[Dubius Cato]

I there anybody who is able to consistently use ambushes on the campaign map?