kenotron vs electron tube

kenotron and electron tube both are nouns.

Word	Noun	Adjective	Verb	Adverb
kenotron	Yes	No	No	No
electron tube	Yes	No	No	No

As nouns, electron tube is a hypernym of kenotron; that is, electron tube is a word with a broader meaning than kenotron:

kenotron: a type of vacuum tube formerly used as a high-voltage rectifier.
electron tube: electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

Other hypernyms of kenotron include thermionic tube, thermionic vacuum tube, thermionic valve, tube, vacuum tube.

kenotron (noun)	electron tube (noun)
a type of vacuum tube formerly used as a high-voltage rectifier.	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope