What is the difference between the VMware vSphere Automation SDK for Perl 6.5 and the vSphere Perl SDK for vSphere 6.5, if any, other than the fact that the second one also includes vSphere CLI.
If they are different, is one perhaps newer and the other deprecated (unlikely though, because of same version numbers)?
They are different SDKs which talk to different APIs.
The vSphere Automation SDK talks to the vSphere Automation REST based APIs. The vSphere Perl SDK talks to the vSphere SOAP based APIs.
One thing to note, the vSphere Automation APIs are fairly new and have some limited coverage (namely: VCSA, VM, Tagging, and Content Library management) compared to the vSphere APIs.