The complete set of Spacemaster:Privateers books is currently being rebranded and will be available in pdf and, all being well, print-on-demand.
As for the difference between 1e and 2e Spacemaster, I think that has more to do with the 1e version having GM Book, Player Book, and Tech Book as separate "books" and 2e rolling all of these into a single large volume and adding the Spacemaster Companion into that, than changes in content per se.
Best wishes,
Nicholas