No, it was a real hypervisor, running VMs (and DOS) in ring 3. They didn't call it VMM32 for nothing.
[0] https://web.archive.org/web/20111110161740/http://blogs.msdn...
[Extra] https://devblogs.microsoft.com/oldnewthing/20130208-00/?p=53...
On the other hand, articles from people like Andrew Schulman and Matt Pietrek (before he got bought out by MS) are far more explicit about the truth.
As for being more advanced than NT, it depends what you consider "more advanced"; a traditional OS, or a hypervisor? It certainly takes some effort to wrap your head around the VxD driver model of the latter, while the former is quite straightforward.