metre vs metric linear unit

metre and metric linear unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
metre	Yes	No	No	No
metric linear unit	Yes	No	No	No

As nouns, metric linear unit is a hypernym of metre; that is, metric linear unit is a word with a broader meaning than metre:

metre: the basic unit of length adopted under the Systeme International d'Unites (approximately 1.094 yards)
metric linear unit: a linear unit of distance in metric terms

metre (noun)	metric linear unit (noun)
rhythm as given by division into parts of equal duration	a linear unit of distance in metric terms
(prosody) the accent in a metrical foot of verse
the basic unit of length adopted under the Systeme International d'Unites (approximately 1.094 yards)