Here's a proper
picture, it is actually MR and RS. Maybe the RS is a low-budget version of the car similar to the cheaper std. B-Max4II (23,000 yens). It is 21,000 yens compared to 28,000 of the current car and 29,190 of the MR, which will most probably include extra gear box parts and accessories like battery mount and rear shock mounts. The chassis in the rear motor car shown
here seems to be the same as the mid-motor. Take a look at the antenna mounts, the battery mount and the saddle pack chassis recesses.
Edit: Found both cars for preorder on super-rc.co.jp at very decent prices. The RS indeed seems to have plastic shocks!