What does `curl -H 'Authorization: Bearer {TOKEN}' https://sentry.io/api/0/projects/` return

I was Reading this

curl -H 'Authorization: Bearer {TOKEN}' https://sentry.io/api/0/projects/
curl -u {API_KEY}: https://sentry.io/api/0/projects/

what would both the statements return ? If I run it by passing the correct TOKEN, API_KEY and URI nothing happens