Different terms for Freeform?

I came from a RP hub where terms are a little different from sites like this.

I think I see "play by post" here instead of Freeform? are there more terms for this then I am aware?

 

I tend to see a few different terms floating around, but I've found that some of the times they are interchangable and other times it's because they're trying to go for a different and more specific type that fits under the Freeform umbrella so to speak?

Play by post, Freeform, Sandbox, Freeplay, Open World, Open Ended, Unstructured/Loosely Structured, Flexible, Player Driven, Character Driven, etc.