test bed vs workplace

test bed and workplace both are nouns.

Word	Noun	Adjective	Verb	Adverb
test bed	Yes	No	No	No
workplace	Yes	No	No	No

As nouns, workplace is a hypernym of test bed; that is, workplace is a word with a broader meaning than test bed:

test bed: a place equipped with instruments for testing (e.g. engines or machinery or computer programs etc.) under working conditions
workplace: a place where work is done

Other hypernyms of test bed include work.

test bed (noun)	workplace (noun)
a place equipped with instruments for testing (e.g. engines or machinery or computer programs etc.) under working conditions	a place where work is done