criticism vs written material

criticism and written material both are nouns.

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

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

criticism: a written evaluation of a work of literature
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 criticism include piece of writing, writing.

criticism (noun)	written material (noun)
a serious examination and judgment of something	the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)
disapproval expressed by pointing out faults or shortcomings
a written evaluation of a work of literature