Sigma 500mm f 5 6 dg dn os sports vs sony fe 300mm f 2 8 gm oss?

Here is what the site says about that.

From Sigma 500mm f/5.6 DG DN OS Sports: Sigma 500mm f/5.6 DG DN OS Sports: A prime lens by Sigma for Full frame cameras, 500mm f/5.6. A comparatively light 500mm prime for wildlife. Specs - Maker: Sigma - Focal length: 500mm (prime) - Maximum aperture: f/5.6 - Made for: Full frame sensors - Mounts: Sony E, L-Mount - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Sony E, L-Mount): as marked, 500mm. - On APS-C (Sony E, L-Mount): like 750mm ...

From Sony FE 300mm f/2.8 GM OSS: Sony FE 300mm f/2.8 GM OSS: A prime lens by Sony for Full frame cameras, 300mm f/2.8. Specs - Maker: Sony - Focal length: 300mm (prime) - Maximum aperture: f/2.8 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 300mm. - On APS-C (Sony E): like 450mm on full frame; f/2.8 gives about the depth of field ...

Quoted from this site's pages.