hall porter vs door guard

hall porter and door guard both are nouns.

Word	Noun	Adjective	Verb	Adverb
hall porter	Yes	No	No	No
door guard	Yes	No	No	No

As nouns, hall porter and door guard are synonyms defined as:

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

hall porter (noun)	door guard (noun)
someone who guards an entrance	someone who guards an entrance