How is a recovery key different from a a password or pin? They are both just a string you need to enter during the recovery process and if you have lost that string you cannot unlock the drive
You have to enter them on every boot before the OS will be able to decrypt the drive. On windows, the key is loaded into memory automatically almost all of the time, and only if it thinks something goes wrong does it suddenly stop working. Or in the case of my colleague, because windows changed his recovery key without notifying him that his backup key was no longer valid. (It deleted it because it thought his key escrow policy had changed, and since that requires generating a new key, it has to delete the old key. Unfortunately escrow policy hadn’t actually changed, so all backup unlocking sources all still had the old key)
They are randomly generated and therefore high entropy.
The difference is that it's neither expected nor practical to memorize your recovery key.