What is different pixhawk 2.4.5 vs 2.4.6 vs 2.4.8?

I’m reading pixhawk schematics. but There exist many version 2.4.5, 2.4.6, 2.4.8…

what is different? and I can’t find 2.4.8 schematic.

The 3DR Pixhawk is 2.4.5 (do a Google search to verify this). As far as I know, no reputable vendor has produced anything else using the info on PX4/Hardware. All available documentation is there, or on the PX4 forums.

Thanks Mark your advice