writing vs body of work

writing and body of work both are nouns.

Word	Noun	Adjective	Verb	Adverb
writing	Yes	No	No	No
body of work	Yes	No	No	No

As nouns, body of work is a hypernym of writing; that is, body of work is a word with a broader meaning than writing:

writing: (usually plural) the collected work of an author
body of work: the total output of a writer or artist (or a substantial part of it)

Other hypernyms of writing include oeuvre, work, black and white, written communication, written language.

writing (noun)	body of work (noun)
the activity of putting something in written form	the total output of a writer or artist (or a substantial part of it)
the act of creating written works
the work of a writer; anything expressed in letters of the alphabet (especially when considered from the point of view of style and effect)
letters or symbols that are written or imprinted on a surface to represent the sounds or words of a language
(usually plural) the collected work of an author