Basically in response to http://www.fantasyflightgames.com/edge_foros_discusion.asp?efid=154&efcid=4&efidt=743847 and with a lack of an updated FAQ…

So we have rules for Ambush and for Raider, but what is 'Experience'? What makes it different from just putting a resource token on the card?

Main reason I ask:

Devoted to Taal - Action: Take target experience attached to a unit or legend you control into your hand . Then, attach this card facedown to that unit or legend as an experience.

Is it the same as playing a development then? but for units?

You don't need a FAQ, there's a rules sheet included in every Eternal War battle pack.