metrical unit vs cadence

metrical unit and cadence both are nouns.

Word	Noun	Adjective	Verb	Adverb
metrical unit	Yes	No	No	No
cadence	Yes	No	No	No

As nouns, cadence is a hypernym of metrical unit; that is, cadence is a word with a broader meaning than metrical unit:

metrical unit: (prosody) a group of 2 or 3 syllables forming the basic unit of poetic rhythm
cadence: (prosody) the accent in a metrical foot of verse

Other hypernyms of metrical unit include beat, measure, meter, metre.

metrical unit (noun)	cadence (noun)
(prosody) a group of 2 or 3 syllables forming the basic unit of poetic rhythm	a recurrent rhythmical series
	the close of a musical section
	(prosody) the accent in a metrical foot of verse