written communication vs written language

written communication and written language both are nouns.

Word	Noun	Adjective	Verb	Adverb
written communication	Yes	No	No	No
written language	Yes	No	No	No

As nouns, written communication and written language are synonyms defined as:

written communication and written language: communication by means of written symbols (either printed or handwritten)

Other synonyms of written communication include black and white.

written communication (noun)	written language (noun)
communication by means of written symbols (either printed or handwritten)	communication by means of written symbols (either printed or handwritten)