lockman vs trained worker

lockman and trained worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
lockman	Yes	No	No	No
trained worker	Yes	No	No	No

As nouns, trained worker is a hypernym of lockman; that is, trained worker is a word with a broader meaning than lockman:

Other hypernyms of lockman include skilled worker, skilled workman.

lockman (noun)	trained worker (noun)
a worker in charge of a lock (on a canal)	a worker who has acquired special skills