Snellen test vs trial

Snellen test and trial both are nouns.

Word	Noun	Adjective	Verb	Adverb
Snellen test	Yes	No	No	No
trial	Yes	No	No	No

As nouns, trial is a hypernym of Snellen test; that is, trial is a word with a broader meaning than Snellen test:

Other hypernyms of Snellen test include run, test.

Snellen test (noun)	trial (noun)
a test of visual acuity using a Snellen chart	the act of testing something
	(law) the determination of a person's innocence or guilt by due process of law
	the act of undergoing testing
	trying something to find out about it
	an annoying or frustrating or catastrophic event
	(sports) a preliminary competition to determine qualifications