A STAR Attestation is an extension of SOC2. STAR Attestation essentially increments the SOC2 by adding the Cloud Control Matrix controls on the top of the Trust Services Criteria.
During the auditing, you will be audited on both sets of requirements. At the end of the process, you will receive both a SOC2 and STAR Attestation. STAR Attestation has both Type 1 and Type 2 options. Please note that only a certified CSA STAR auditor can perform the attestation audit.