Actually I consider it a considerable difference as in H3 you also have the option of "Surrendering" and keeping what's left of your army ounce you rehire the Hero. Not to mention it's INSTANT rehire in both cases no waiting a couple turns for hero to make it back to castle.

Hehe I knew that was coming, but seriously, how often does anyone use surrender in Heroes of MM. Flee is the only viable option, and it is not much different.