In the Fabric-CA Client’s CLI documentation(https://hyperledger-fabric-ca.readthedocs.io/en/release-1.4/clientcli.html) , there are two commands named "enroll" and "reenroll" respectively. Could any expert tell me the difference between them? Thanks.
Enroll command is used to enroll the user for the first time with the CA.
There could be cases when a certificate expires or gets compromised (so it has to be revoked). So this is when re enrollment comes into the picture and you enroll the same identity again with the CA to get new certificates.
Additional Note about Revocation of certificates:
Revocation can be done for a number of reasons (exactly 10), also when revoking please don't forget to update the CRL(Certificate Revocation List).
Please go through these sections of the documentation for a better understanding of the same: