Fudge is half a tabletop RPG and half a toolbox for building your own tabletop RPG. There aren't any default rules, just a bunch of different ways of doing the same thing. The idea is that each GM would customize the game to fit their preferences.
Fudge Lite is my personal build of Fudge, made to be as light as possible without sacrificing playability. The core rules are about five pages, and the rest of the document is just examples and alternate rules you can use.
To clarify: Fudge is not the same thing as Fate. Fate was a build of Fudge that started out as just "Fudge with aspects" and over time it evolved into its own thing. At this point, the only things Fate and Fudge have in common are the dice and about two-thirds of Fate's adjective ladder.