RequestCertificate will create a certificate signing request using the PEM encoded CSR and send it to API server, then it will watch the object's status, once approved by API server, it will return the API server's issued certificate (pem-encoded).

RequestNodeCertificate will create a certificate signing request for a node (Organization and CommonName for the CSR will be set as expected for node certificates) and send it to API server, then it will watch the object's status, once approved by API server, it will return the API server's issued certificate (pem-encoded).