The list consists of all updates that have ever been installed for which the Windows Update Agent has a record. This includes updates that have been superseded and/or subsequently uninstalled, So the list is not just the currently installed updates.
The Status column can include an error code which may need to be interpreted in the absence of a corresponding message. The list of error codes is available on Microsoft's MSDN site.
Also note that an error code may also be returned in the event of a successful installation; for example, the error code 0x240006 may be present to indicate that an update did not install because it was already present on the device.