Leica super elmar m 21mm f 3 4 asph vs voigtl nder color skopar 21mm f 4 p?

Here is what the site says about that.

From Leica Super-Elmar-M 21mm f/3.4 ASPH: Leica Super-Elmar-M 21mm f/3.4 ASPH: A prime lens by Leica for Full frame cameras, 21mm f/3.4. A small 21mm; needs an external finder, live view or an EVF. Specs - Maker: Leica - Focal length: 21mm (prime) - Maximum aperture: f/3.4 - Made for: Full frame sensors - Mounts: Leica M - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Leica M): as marked, 21mm. Cameras it fits ...

From Voigtländer Color-Skopar 21mm f/4 P: Voigtländer Color-Skopar 21mm f/4 P: A prime lens by Voigtländer for Full frame cameras, 21mm f/4. Specs - Maker: Voigtländer - Focal length: 21mm (prime) - Maximum aperture: f/4 - Made for: Full frame sensors - Mounts: Leica M - Stabilised: no - Autofocus: no, manual focus What it frames like - On full frame (Leica M): as marked, 21mm. Cameras it fits - Leica M9: Full frame - Leica M9-P: Full frame - [Leica ...

Quoted from this site's pages.