-is there a list of differences between 1st and 2nd edition?
I don't think so- the changes were pretty significant. http://boardgamegeek.com/thread/574838/the-new-haunts-are-im... has the numbers of the completely new haunts, there are a few new Item cards, and a lot of errata has been incorporated. You can get most of the errata by downloading the updated Traitor's Tome and Secrets of Survival from Wizards' website, if you haven't.
-can i play the scenarios from 2nd with the components of the 1st?
I'd have to look at the haunts to know for sure, but probably. The 2nd edition comes with more generic monster tokens, so whenever you see "red token" you'd use a Bat instead or whatever.