arms vs coat of arms

arms and coat of arms both are nouns.

Word	Noun	Adjective	Verb	Adverb
arms	Yes	No	No	No
coat of arms	Yes	No	No	No

As nouns, arms and coat of arms are synonyms defined as:

Other synonyms of arms include blazon, blazonry.

arms (noun)	coat of arms (noun)
weapons considered collectively	the official symbols of a family, state, etc.
the official symbols of a family, state, etc.