Seems like the same camera — with cosmetic and UI/UX differences:

Leica SL2 as simpler, better aesthetics

SL2 also seems thinner, probably lighter.

Specs

Lumix S1R:

Leica SL2:

Which to get?

If you want a sexier body, and more luxury approach, get LEICA SL2.

If functionality is all you care for, get Lumix S1R.

I believe both cameras share the same sensor.