It's the same story, though with a new title I can feel some paragraphs wanting to align themselves with the new title instead of the old--but the book's in production now. Titles decided on early affect the story while it's being written. Titles decided on late have much less (often no) effect on the story.
Titles are a strange form of writing. The title needs to convey something about the book--and if in a group of books with a single story arc, it needs to connect to the other books and their titles. It also needs to intrigue the right readership and resonate with the various themes and plots and subplots, so readers don't put it down thinking "How does that title relate to that text???" Titles can suggest genre and even subgenre: right now, non-mystery-genre titles with "blood" in them strongly suggest vampire stories. Like cover art, titles are mostly connected to marketing, but by being words, titles also connect to the text of the story itself.
And that's why the thesauruses and dictionaries and pads of paper were in use in three different offices. Echoes of Betrayal will be out sometime next spring.