kind of the whole point behind it was wanting to decouple the Powershell release cadence from that of Windows, getting updated versions of things in Windows is -hard-

Powershell 7 (which just dropped RC2) is the Powershell going forward, it's based on .NET Core, its xplat, it's the one with all the dev resources assigned to it

Windows Powershell ships with windows, and is still at 5.1 at last check

Powershell Core 6 will be the only major version of Powershell core, 7 drops the core moniker