I tend to think of them as learning vs sharing tools and techniques.
Descriptive artifacts give you and your team a way to analyze what is needed or what the current user process is. I'm a firm believer in the Jobs to Be Done framework so these artifacts let you identify the real reason for a hire.
I like prescriptive artifacts as a way to share findings with the rest of the team. User Stories, Journey Maps, etc give you a way to share the analysis of raw information in a package that other makers can get behind. I don't think it's an accident that Agile Methodology employs User Stories to help developers know what to build and allow QA to understand what success looks like.