A
hand written,
hand typed or otherwise
unique book or other
written work.
The word manuscript emphases a book's unique properties, whether it is a illuminated, copied-by-hand, pre-Gutenberg bible, the copy of a play or novel that a hopeful amateur has submitted to a publisher in the hopes of discovering in themselves the next John Grisham or a private hand written diary kept by a housewife documenting her inner thoughts that's only discovered by her family after she passes away.
Qualities that don't make a work a manuscript include hand bookbinding (because this doesn't influence the intellectual content of the work) and very high quality printing (this influences the market price of the work, not its intellectual content).