Depends on what you mean by improvement.
The Drive 2's cushioning is firmer than the 1's, and that might be considered an improvement by many. Not necessarily to me. I said it before, I'd take the 2's if I'm only playing one important game and the 1's for normal, longer sessions. Much prefer the Micro G in the first Drive.
Crazy as it might sound, my opinion is the Spawn/CF Drive era was the peak of UA basketball so far and it's kind of been either a plateau or a bit downhill. I can't say the Curry 1 and 2 are better performers than the Spawn/Drive.
Pure speculation: I think UA reeled in a bunch of fans with Micro G in the Black Ice, Bloodline, Spawn, and Drive, then pulled a Nike with their poor implementations of Zoom and gave us Charged. I know a lot of people like Charged, but if I had to choose between Micro G and Charged it's a no brainer.