As a man hunting down every freaking possible officially released variant, there really is no difference between the games as far as the K-A / E rating goes. For whatever reaosn they wanted single letter only across the board, and did away with it. Hence why there is now E+10 rather than like, PT (Pre-Teen). They just simply changed the icon when they re-released the game as a GH.
There are several US Gold long box games that had the K-A replaced with E once Eidos bought them out and republished them in the jewel case size.
It's usually more if a buyer wants the Non GH or GH version of a game.
The only real game I can think of other than GTA that had a ESRB change (per se) just without all of the dipshit hype and political riding was Final Fantasy VII.
The original release was a Teen for "Realistic Violence", which was hogwash. The game was then re-released as a Teen (+13) with the reasosn of being Comic Mischief (Caet Sith), Mild Language (Most of Barrett's Speech), and Mild Animated Violence (not even Sephiroth's sword drew blood, if ya know what I mean).
You can see the two
here, or you can check out the (now outdated) PlaySTation variant page at
http://www.game-rave.com/variant/index.html
Main page at
http://www.game-rave.com/psx
Jason