Remastering is a process in which you take the original music track in its purest form right after mixing, when it hasn't gone through any final audio processing yet, and apply equalization, compression, possibly stereo image fixing, stereo enhancing or exciting and finally limiting. Perhaps adding other processing effects in the fx chain as well.
I once read on a Mark Morgan interview that if he only could find the original masters of the Fallout music he composed, he would re-release them remastered and as better quality files. Seems like he finally found them then. I have been looking forward to this day for some time now.
Ooh yes, I just realized, the Modoc theme remastered and in better quality, finally!
Edit:
Getting pops and clicks on "Industrial Junk" at least. Can't say if it's intentional, but annoying.