VMware titles its interm releases as “Update 1” or “Update 2”, etc. But in vSphere client, the version is displayed with a build number. And in the VMware HCL, the versions are displayed using the “Update” number.

Trying to make sense of this can be difficult, but luckily Virten.Net (@viFlorian) has an ESXi Release and Build Number History page which helps make sense of it all.

On a related note, if you need to decipher a SQL Server build number and relate it to version and service pack, check out SQLServerBuilds.