doorkeeper vs door guard

doorkeeper and door guard both are nouns.

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

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

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

doorkeeper (noun)	door guard (noun)
someone who guards an entrance	someone who guards an entrance
an official stationed at the entrance of a courtroom or legislative chamber
the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church