What is secret parameter in register call

In ETH Registrar Controller 2 smart contract, the function call register has a parameter “secret” and fucntion call commit has a parameter commitment. Are they the same, or not? If not how to generate the secret parameter.

The ‘secret’ value is an arbitrary nonce made up by the caller, and passed in to makeCommitment to generate a commitment, and register to reveal it. It should be a random value generated by the client and never reused.