coat of arms vs blazonry

coat of arms and blazonry both are nouns.

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

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

coat of arms and blazonry: the official symbols of a family, state, etc.

Other synonyms of coat of arms include arms, blazon.

coat of arms (noun)	blazonry (noun)
the official symbols of a family, state, etc.	the official symbols of a family, state, etc.