Kad said: "I wasn't aware the book had been revised in a substantial way for the 2010 revival- what are the differences?"
The version of the script that Harvey tailored to himself during his run in the show is now the standard. So there's a line about Georges being younger than Albin, lines inspired by the costumes he wore, those impressions that Harvey did during the cabaret numbers are now part of the text (and the music around it reflects that), there's a counter melody and new lyrics for "With You On My Arm" (see 2010 cast album), there are 6 Cagelles instead of 12, Jacob is Latin American instead of Black, and there are sharper jokes that feel more in line with the politics of today, rather than the cautiousness of 1983.
Some of it was a matter of Harvey removing Arthur Laurents-isms.
Jerry & Harvey also liked the show being smaller...Albin & Georges wouldn't run a Vegas-style nightclub as seen in the 83 and 04 productions, it would be grungier.
To the naked eye, the versions probably look quite similar, but from the author's standpoint he preferred the revision. And the changes are big enough that you can't just use the old scores with the new book without someone adapting the orchestrations & arrangements.
I did some quick Googling and I think these are the two script versions: