Some bridges were modified, and it sounds like the vocals are more pronounced, but the real deal's with the added strings in the background. My god they bring out the song so much more. Awesome song gets more awesome.
Side note, Melvin had me listen to Trivium's cover of Master of Puppets (I'm lagging, I know.) and I don't know if I can say I like the original better. Fantastic cover by Trivium. Now to check out some Apolcalyptica stuff, apparently they do wicked cello covers of Metallica songs.
Oh and yes, there is a difference in quality between using a phone to play music and using an iPod. Where's my fucking iPhone now?