canopy vs tester

canopy and tester both are nouns.

Word	Noun	Adjective	Verb	Adverb
canopy	Yes	No	Yes	No
tester	Yes	No	No	No

As nouns, tester is a hyponym of canopy; that is, tester is a word with a more specific, narrower meaning than canopy:

canopy: a covering (usually of cloth) that serves as a roof to shelter an area from the weather
tester: a flat canopy (especially one over a four-poster bed)

Other hyponyms of canopy include awning, sunblind, sunshade, baldachin, marquee, marquise, porte-cochere, umbrella.

canopy (noun)	tester (noun)
a covering (usually of cloth) that serves as a roof to shelter an area from the weather	a flat canopy (especially one over a four-poster bed)
the umbrellalike part of a parachute that fills with air	someone who administers a test to determine your qualifications
the transparent covering of an aircraft cockpit

canopy (verb)	tester (verb)
cover with a canopy