Hello Onyi
The command crypto isakmp key command is used to configure a preshared authentication key. The crypto keyring command, on the other hand, is used to create a repository of preshared keys. The keyring is used in the ISAKMP profile configuration mode. The ISAKMP profile successfully completes authentication of peers if the peer keys are defined in the keyring that is attached to this profile.
The term keyring is used to denote that the keyring includes multiple preshared keys, much like a physical keyring contains many keys. For more information about creating and maintaining keyrings, take a look at the following Cisco documentation.
I hope this has been helpful!
Laz