my understanding is that the machinery underlying it are a bit more complex than what terraform would do.

if anything that would be because the kubernetes operators implementing the Cluster API for your specific cloud provider would be implemented in a continuously running control loop, thus picking up changes... whereas with terraform you would have to run terraform from time to time.

edit: plus of course all the other features coming from kuernetes like mutating admission, validation, rbac (eg: only allow some people to create clusters or allow people to create clusters without granting access to the underlying cloud provider) etc etc...