there is a lot of confusion here, so let's straighten this out.
- there is no code/binary difference between "vSphere ESXi" and "VMware Hypervisor" or "VMware Free Hypervisor". it's one and the same thing. the feature set is controlled by the license key that you use.
- the free hypervisor license is "VMware vSphere Hypervisor 6 License". this covers 6.0 and 6.5 with all patches
- for any release of ESXi there is not always going to be a new ISO file cut. sometimes you need to patch to get the latest code.
- patches are available from https://my.vmware.com/group/vmware/patch
- there are patches (released in december 2017) which are newer than update 1 (released in july 2017)
- regardless if you start with 6.5.0a or 6.5U1 you still need to patch if you want the latest release.
at this point in time, the free hypervisor download has an ISO for 6.5.0a only. you can download and install this, and then patch it up to the current release.
alternatively you can download the "trial" version of 6.5U1 in order to get the latest ISO and use your free hypervisor license. if you want the latest code, you will still need to patch it up.
you could also take the advantage to download one of the "Custom ISOs" if you have a HP, IBM, Lenovo etc server and want an ISO with embedded hardware support for your platform.
in most situations, the Custom ISOs aren't the latest release and require patching.
i hope this helps.
cheers, wizdude.