It's different than Remastered in that there's more content - a 400 hex map, new art, new layout, some new lore and world-content. I feel like the actual rules are generally very similar to Remastered. Probably some bugfixes.
I bought Remastered before I ever got the original edition, didn't know the OG had a solo-rules setup. This one has a new version of that, one I think is an improvement and quite nice.