GetAuthToken contacts the API endpoint https://github.com/login/oauth/access_token to check if you entered the user-code and if you entered the user-code, it gets the token generated by GitHub.

Init contacts the API endpoint https://github.com/login/device/code to get a device-code needed for getting an auth-token and a user-code, which is what you enter at https://github.com/login/device to get an auth-token.