The plot slightly differs (it's about search for the "SoS" system). 0.99b - second released version and original first version of the plot. 1.02 - the officially final version by developer. Has additional content, including small locations, the companion-dog and some easter eggs. It's a "Fallout: Nevada - Fixed edition" with english translation (with narration) and sfall, configurator, IFP, HRP and many bug-fixes. (LATEST) Fallout: Nevada - Complete mod.0.99a - first major version, released in april, 2011.
0.99c- test-version for limited number of users. Content also differs by ~ 30-35% (plot, some dialogs, some quests, differences in locations and endgame bosses.) Basically, version 1.02 with restored content and loads of bug-fixes. It's a "Fallout: Nevada - Fixed edition" with english translation and narration, sfall, configurator, IFP, HRP and many bug-fixes.