What's the line between prose and purple prose?

So I have this outline (will post an example in comments in case you want to give examples)

Like I already have all the info in the outline itself, what to do to convert it to an immersive experience? Not purple prose?

In other words: what is it missing that counts as "immersion" but is not "purple prose"?

I do know that flowery language is disorienting, but that's not everything, I'm trying to understand the usage of simple words without making the experience dry