agate line vs area unit

agate line and area unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
agate line	Yes	No	No	No
area unit	Yes	No	No	No

As nouns, area unit is a hypernym of agate line; that is, area unit is a word with a broader meaning than agate line:

agate line: space for one line of print (one column wide and 1/14 inch deep) used to measure advertising
area unit: a system of units used to measure areas

Other hypernyms of agate line include square measure.

agate line (noun)	area unit (noun)
space for one line of print (one column wide and 1/14 inch deep) used to measure advertising	a system of units used to measure areas