gatekeeper vs door guard

gatekeeper and door guard both are nouns.

Word	Noun	Adjective	Verb	Adverb
gatekeeper	Yes	No	No	No
door guard	Yes	No	No	No

As nouns, gatekeeper and door guard are synonyms defined as:

Other synonyms of gatekeeper include doorkeeper, doorman, hall porter, ostiary, porter.

gatekeeper (noun)	door guard (noun)
someone who guards an entrance	someone who guards an entrance
someone who controls access to something