I looked through the comparison tool, and it seems that the tippity top tier is the absolute newest with all the latest. The second tier uses a narrower fork, older tires, older saddle but on the latest frame, and the third from the top is using older frame geometry, because the seatpost information includes different sizing specs, plus all the other stuff. At this level it's a strong argument for selling one version, and if you want something different buy a frame for a custom build. Do you think they have purchase contracts with Shimano and SRAM and this is how they sell the extra?

I'm not seeing much to sway me from the cheaper models, since any modern MTB I could purchase would be an order of magnitude different from my 1989 Kona.