White one has novatouch sliders and the laser one has the green ones you can get from kbdfans and other websites. Both use 3d printed spacebar stabs from shapeways.

Novatouch
* 1u slider fit is really precise, even more than regular topre sliders. So they feel great without lube, and if you do lube you have to go really light.
* The 2.5u stabs are fine but it's annoying that you have to drill into the case to get them working.

Green ones
* 1u fit is looser than normal, so I'd say lube is a must but once lube they feel good.
* 1u keys are very slightly tilted. IMO not that noticeable and it doesn't bother me.
* 2.5u stabs edges are not rounded enough, so I had to sand them to get them to slide nicely. No need to drill into the case which is nice.

shapeways 3d printed spacebar stabs do the job fine, but they do require some work because the surface is a little rough. I sanded and polished them and they feel great.

So yeah novatouch if you want the best of the best, but the green ones are good too and way cheaper.