printing vs test copy

printing and test copy both are nouns.

Word	Noun	Adjective	Verb	Adverb
printing	Yes	No	No	No
test copy	Yes	No	No	No

As nouns, test copy is a hyponym of printing; that is, test copy is a word with a more specific, narrower meaning than printing:

Other hyponyms of printing include edition, proof, trial impression, mackle.

printing (noun)	test copy (noun)
the business of producing printed material for sale or distribution	(printing) an impression made to check for errors
reproduction by applying ink to paper as for publication
text handwritten in the style of printed matter
all the copies of a work printed at one time