There are two ways vCenter comes packaged: An installer for Microsoft Windows; and a pre-built, Linux-based appliance. For your purposes, you should always use the vCenter Server Appliance (vCSA) as the Windows version is dead and will not be continued. Either one gives you vCenter Server, but really your only choice is the appliance at this point.
Like many non-Windows appliances, the vCSA appears to be more forgiving as it needs roughly half the hardware requirements as a Windows box.
That may make it easier to re-purpose any old hardware that can't pass for a useful host.
The Windows version does have the ability to run on anything, server or desktop or laptop perhaps.
So then VCenter for Windows is only around for legacy reasons ?
At this point, yes.