metrical foot vs dactyl

metrical foot and dactyl both are nouns.

Word	Noun	Adjective	Verb	Adverb
metrical foot	Yes	No	No	No
dactyl	Yes	No	No	No

As nouns, dactyl is a hyponym of metrical foot; that is, dactyl is a word with a more specific, narrower meaning than metrical foot:

metrical foot: (prosody) a group of 2 or 3 syllables forming the basic unit of poetic rhythm
dactyl: a metrical unit with stressed-unstressed-unstressed syllables

Other hyponyms of metrical foot include iamb, iambus, anapaest, anapest, amphibrach, trochee, spondee, dibrach, pyrrhic, iambic trimeter.

metrical foot (noun)	dactyl (noun)
(prosody) a group of 2 or 3 syllables forming the basic unit of poetic rhythm	a finger or toe in human beings or corresponding body part in other vertebrates
	a metrical unit with stressed-unstressed-unstressed syllables