Archiver
Veteran
I own the Panasonic 50mm f1.8 and the Leica Summicron 35mm f2 SL ASPH. The following video suggests that there is little to no difference between the Panasonic and Leica versions of these lenses:
What I can say is that the Leica is heavier, has a more luxuriously damped focus ring, and feels better in the hand. It apparently has better weather sealing than the Panasonic version as well. Combined with the SL2-S and some judicious processing, the images are startlingly rich and lifelike. They have a sense of transparency and clarity that I really enjoy.
SL2-S - Fat burning by Archiver, on Flickr
Leica SL2-S | Leica Summicron SL 35mm f2 ASPH
SL2-S - Place your life in my hands by Archiver, on Flickr
Leica SL2-S | Leica Summicron SL 35mm f2 ASPH
What I can say is that the Leica is heavier, has a more luxuriously damped focus ring, and feels better in the hand. It apparently has better weather sealing than the Panasonic version as well. Combined with the SL2-S and some judicious processing, the images are startlingly rich and lifelike. They have a sense of transparency and clarity that I really enjoy.

Leica SL2-S | Leica Summicron SL 35mm f2 ASPH

Leica SL2-S | Leica Summicron SL 35mm f2 ASPH