write copy vs writing

write copy is not a noun while writing is a noun.

Word	Noun	Adjective	Verb	Adverb
write copy	No	No	Yes	No
writing	Yes	No	No	No

write copy (noun)	writing (noun)
	the activity of putting something in written form
	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

write copy (verb)	writing (verb)
write for commercial publications