SOC 1 reports. Primarily an auditor-to-auditor communication, these address the controls at a service organization relevant to financial reporting. These are restricted use reports, not designed for promotional purposes.
SOC 2 reports. SOC2 is a response to the rapid growth in cloud computing and data outsourcing, They help clarify how reports on non-financial controls regarding information, such as data security, confidentiality and privacy should be structured.
SOC 3 reports. These cover the same subject matter as SOC 2, but in a general use, short form format which may be freely distributed.