lockkeeper vs trained worker

lockkeeper and trained worker both are nouns.

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

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

Other hypernyms of lockkeeper include skilled worker, skilled workman.

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