lighthouse keeper vs steward

lighthouse keeper and steward both are nouns.

Word	Noun	Adjective	Verb	Adverb
lighthouse keeper	Yes	No	No	No
steward	Yes	No	No	No

As nouns, steward is a hypernym of lighthouse keeper; that is, steward is a word with a broader meaning than lighthouse keeper:

Other hypernyms of lighthouse keeper include custodian, keeper.

lighthouse keeper (noun)	steward (noun)
the keeper of a lighthouse	someone who manages property or other affairs for someone else
	a union member who is elected to represent fellow workers in negotiating with management
	one having charge of buildings or grounds or animals
	an attendant on an airplane
	the ship's officer who is in charge of provisions and dining arrangements