So, Ur-Quan Masters is a remake of the original with a few quality of life improvements that was spurred along by the original creators (Paul and Fred) after the license for the Star Control name (but not the content) went elsewhere.
As to why you’d buy the original at this point, well, I guess if you really want the authentic experience, bugs and all. But otherwise UQM will give you everything in a little nicer package.
My friends and I used to play this a ton, but never as a flight sim. We loved the movie making mode so much, as it was a tool so unlike anything else out there at the time. You could set up some incredibly elaborate scenes that more or less played themselves out on their own. And then being able to edit all the footage together with sound and special effects? Amazing stuff.
I grabbed it off GoG when it popped back up, and though the interface hasn’t aged well, the core is still super fun.