man-of-war bird vs frigate bird

man-of-war bird and frigate bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
man-of-war bird	Yes	No	No	No
frigate bird	Yes	No	No	No

As nouns, man-of-war bird and frigate bird are synonyms defined as:

man-of-war bird and frigate bird: long-billed warm-water seabird with wide wingspan and forked tail

man-of-war bird (noun)	frigate bird (noun)
long-billed warm-water seabird with wide wingspan and forked tail	long-billed warm-water seabird with wide wingspan and forked tail