It might be better to ask this question at the Movie Studio forum rather than here at the Vegas Pro forum.
But that said, there is a major difference between Vegas Movie Studio (with ran up through version 17) and Vegas Studio 2022 (an entirely different program created by Magix). One is not really a successor to the other.
Movie Studio 18 and newer (i.e. 2022) is a renamed Magix Movie Edit Pro and shares nothing with Movie Studio 17 and older (i.e. 15) which is VEGAS based.
In reality, the "upgrade" for Movie Studio 15 would be VEGAS Pro 19.
I've corrected the topic title from "Difference between Vegas Movie Studio 15.0 and Vegas Studio 2022" to "Difference between Vegas Movie Studio 15.0 and Movie Studio 2022". There is no "Vegas Studio 2022".