The difference between generative writing and drafting is:
generative writing brings up ideas, drafting develops one idea.
generative writing develops one idea, drafting revises the idea.
generative writing is more specific than drafting.
generative writing is done with more precision than drafting

generative writing brings up ideas, drafting develops one idea.

Explanation:

Generative writing is the main process by which authors and people can brainstorm ideas, you can get a lot of ideas and topics to write about, and then in the drafting part of the process you develop one of those ideas, the main difference between the two is that in the drafting you are already making and developing an idea, while in generative writing you are just coming up with ideas to write about.

what are the phrases to choose from?

they would have to clean it very clean