Sony fe 100 400mm f 5 6 8 oss vs sony fe 100 400mm f 4 5 gm oss?

Here is what the site says about that.

From Sony FE 100-400mm f/4.5 GM OSS: Sony FE 100-400mm f/4.5 GM OSS: A zoom lens by Sony for Full frame cameras, 100-400mm f/4.5. A constant f/4.5 telephoto zoom for sport and wildlife, sold alongside the older f/4.5-5.6. Specs - Maker: Sony - Focal length: 100-400mm (zoom) - Maximum aperture: f/4.5 - Made for: Full frame sensors - Mounts: Sony E - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 100-400mm. - On APS-C ...

From Sony FE 100-400mm f/5.6-8 OSS: Sony FE 100-400mm f/5.6-8 OSS: A zoom lens by Sony for Full frame cameras, 100-400mm f/5.6-8. A light (about 650 g), affordable 400mm zoom. Specs - Maker: Sony - Focal length: 100-400mm (zoom) - Maximum aperture: f/5.6-8 (it gets darker as you zoom in) - Made for: Full frame sensors - Mounts: Sony E - Stabilised: yes - Autofocus: yes What it frames like - On full frame (Sony E): as marked, 100-400mm. - On ...

Quoted from this site's pages.