Do they have their own model? I thought Copilot was a frontend for Clause et. al..

To the best of my knowledge, Copilot is a Microsof in-house thing and it sucks on everything. Claude is far superior and Microsoft is allegedly using Claude internally over its own AI solution.

Github Copilot is just a front-end. You pay for the frontend and some premium requests every month.

The base models like GPT 4o, 4.1 don’t have a usage cap. Models like Claude Sonet, Opus, etc have a monthly limit and you can pay more to use these through Github Copilot.