Two very different shapes and feel. However the Space Cowboy is much better on everything. Spin times, smoothness and stability, ease of doing tricks, etc. My Space Cowboy feels like it plays better than the price whilst the Next Level feels like it under-performs for the $125 price tag.
The Nifty on the far left of the picture, that performs better than the Next Level as well and it is significantly cheaper. I only bought the Next Level because my local yoyo store had a huge sale at the time and I took advantage of that and bought the Next Level for about only… I don’t remember exactly, but to take a guess, it’d be $75?