So, what IS the difference between an assessment and a review? It's true that some publishers say "we'll be back in touch when we've had a chance to review your manuscript", but what they mean is "we will read this and consider it for possible publication".
Generally, a review is understood to mean a reader's reaction to a published book (or film, or album). A reader, who may or may not be an industry professional, reads the book and then writes a response which might include a blurb or synopsis, a few comments on how or whether the book fits its genre and the reviewer's expectations, and a run down of the strengths and weaknesses perceived in the story. Reviews can be 95% blurb and 5% comment. They can even be nothing but the book's blurb or publisher's publicity material reproduced. Some are puff pieces, and others, unfortunately, qualify as hatchet jobs. The best reviews, in my opinion, come from someone knowledgeable enough to review the book in context and also fair enough to mix disinterested or objective comment with personal response. It is generally agreed that reviews should not reveal too much of the plot and certainly not the denouement, and that they should be written grammatically. Most reviewers are not paid for their work. The complimentary copy of the book is considered enough. And of course, some readers buy a book in the usual way and choose to review it in the spirit of sharing opinion with others.
An assessment, on the other hand, is an over view of a manuscript in relation to both its impact as a book of the appropriate genre and to its potential as a publishable work. After some broad comment on what is working well in the ms, the assessor will concentrate on the weaknesses and possible problems along with specific advice on how to fix these. Manuscript assessors are paid for the job by the author, unless they are employees of a publishing company, in which case the assessment will be part of their job description.
So - assessment or review? They are different, and if you approach http://www.affordablemanuscriptassessments.com you are (or should be) after an assessment rather than a review.