NT is a new design by the people who were involved in VMS. Even when they didn't replicate everything, they had already acquired "taste" and "experience" so some solutions of some problems are very similar, to the point that knowing some detail in one OS gives you a good knowledge about the basics of the detail in another. But this is only in some aspects. There are a lot of important solutions that were made for the first time only in the NT.

The team developing NT had the requirements to fulfill that were never put in front of them, and their result was at the end something in many aspects fundamentally better than any competition. There are of course some aspects that the competition did better too, but that was not enough to win the market.

Whoever really wants to learn more about how it was made, including a lot of details about the humans involved, should read the very good written book

"Show Stopper!: The Breakneck Race to Create Windows NT and the Next Generation at Microsoft" (1994) by G. Pascal Zachary