I don't mean to be that guy but TLDR the differences between R1 and R2?
Basically, in r1 all sliders were the same colors. Now the weight will decide the slider color.
R1 also only had up to 67g, and there were linear and tactile versions. It looks like this buy will only have tactile switches, and they go up to 78g.
Also, there appears to be a 65g version with a milky bottom, which will be more heat resistant, if you're concerned about the issues that some others had when they built their boards. Imo, it isn't necessary, but I also had zero issues with the r1 zealios.