rmm36L2 is a bit more comfortable thanks to additional padding, the detachable cable detaches at the cup rather than on the cord itself, and the L2 has a much better headband.
The L2 is a bit more lively than the L1. I found that it had a slight V emphasis compared to the L1's sound. The grills are a bit bigger on the L2 so that could lead to the change in sound signature that I heard. As a result of the grill size change the L2 leak a bit more sound in and out but that's not much of an issue if you're coming from the L1 since they too are semi-open.
And orange if my favorite color, so bonus points there. :p