Moving a mod game from 1 computer to another

I usually create a game on one computer (usually modded somewhat). I start the
game and save it.

Then when I take the saved game to my home computer where I do most of my playing,
does the mod directory for the two computers have to be the same. Or is the modding
saved in the saved game file? And can it be moved anywhere?

The only modding I am doing is on the planetimprovements.xml file.