falcon vs merlin

falcon and merlin both are nouns.

Word	Noun	Adjective	Verb	Adverb
falcon	Yes	No	Yes	No
merlin	Yes	No	No	No

As nouns, merlin is a hyponym of falcon; that is, merlin is a word with a more specific, narrower meaning than falcon:

falcon: diurnal birds of prey having long pointed powerful wings adapted for swift flight
merlin: small falcon of Europe and America having dark plumage with black-barred tail; used in falconry

falcon (noun)	merlin (noun)
diurnal birds of prey having long pointed powerful wings adapted for swift flight	small falcon of Europe and America having dark plumage with black-barred tail; used in falconry

falcon (verb)	merlin (verb)
hunt with falcons