CRT vs Crookes tube

CRT and Crookes tube both are nouns.

Word	Noun	Adjective	Verb	Adverb
CRT	Yes	No	No	No
Crookes tube	Yes	No	No	No

As nouns, Crookes tube is a hyponym of CRT; that is, Crookes tube is a word with a more specific, narrower meaning than CRT:

CRT: a vacuum tube in which a hot cathode emits a beam of electrons that pass through a high voltage anode and are focused or deflected before hitting a phosphorescent screen
Crookes tube: the original gas-discharge cathode-ray tube

Other hyponyms of CRT include kinescope, picture tube, television tube.

CRT (noun)	Crookes tube (noun)
a vacuum tube in which a hot cathode emits a beam of electrons that pass through a high voltage anode and are focused or deflected before hitting a phosphorescent screen	the original gas-discharge cathode-ray tube