Cimorene

;-)

Definitely free will and doing good as a choice is the important thing there, for both of them. Aziraphale has to choose action as well, and it's pretty clear that he's a fairly lazy angel, as well as idolatrous by official standards (he worships books, after all).

A really big difference, for Crowley at least, is what exactly he curses - in the show it's the Great Plan at the bandstand scene, but in the book it's everything:

"Wet and steaming, face ash-blackened, as far from cool as it was possible for him to be, on all fours in the blazing bookshop, Crowley cursed Aziraphale, and the ineffable plan, and Above and Below."

He's renounced Satan and all his works - and everyone else and their works too. He claims more and more free actions after this, even if he might not recognise the freedom until the end. (He chooses first to desert, then changes his mind to try to get to Tadfield, to drive madly across London, under the Thames, etc, decides effectively to destroy the Bentley even before reaching the M25 and so on).

Of course, he also hates anyone pointing out when he has chosen to do something good or good(ish) :-)