falcon vs kestrel

falcon and kestrel both are nouns.

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

As nouns, kestrel is a hyponym of falcon; that is, kestrel 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
kestrel: small Old World falcon that hovers in the air against a wind

falcon (noun)	kestrel (noun)
diurnal birds of prey having long pointed powerful wings adapted for swift flight	small Old World falcon that hovers in the air against a wind
	small North American falcon

falcon (verb)	kestrel (verb)
hunt with falcons