manuscript vs written material

manuscript and written material both are nouns.

Word	Noun	Adjective	Verb	Adverb
manuscript	Yes	No	No	No
written material	Yes	No	No	No

As nouns, written material is a hypernym of manuscript; that is, written material is a word with a broader meaning than manuscript:

manuscript: the form of a literary work submitted for publication
written material: the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)

Other hypernyms of manuscript include piece of writing, writing.

manuscript (noun)	written material (noun)
the form of a literary work submitted for publication	the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)
handwritten book or document