Both read the book and refuse to write it.
This is the rare comparison where DraftProse and the other tool agree on the hard part. Marlowe is analytical, not generative: it reads your manuscript like a developmental editor and reports back, and it never drafts a sentence for you. DraftProse draws exactly the same line. Neither will write your book.
So the choice is not about whether the AI writes. It is about the shape of the thing you are buying: a report, or a room.