sergeant at arms vs serjeant-at-arms

sergeant at arms and serjeant-at-arms both are nouns.

Word	Noun	Adjective	Verb	Adverb
sergeant at arms	Yes	No	No	No
serjeant-at-arms	Yes	No	No	No

As nouns, sergeant at arms and serjeant-at-arms are synonyms defined as:

sergeant at arms and serjeant-at-arms: an officer (as of a legislature or court) who maintains order and executes commands

sergeant at arms (noun)	serjeant-at-arms (noun)
an officer (as of a legislature or court) who maintains order and executes commands	an officer (as of a legislature or court) who maintains order and executes commands