I had an in-depth but incomplete comparison at both the standard multiplayer ruleset, which GT03 is based upon, and re-wonder.
Multiplayer ruleset is just the modernized version of re-wonder.
Most of the differences are about l10n support (translation to foreign languages) and textual corrections to the help messages contained inside the rulesets. There are no differences about units, terrains, buildings, technologies, nor at their requirements or effects, except for the following additions present in multiplayer ruleset: fundamentalism government, elephant unit, fanatic unit.
So far this is an analysis of 70% of the rulesets files.