klystron vs electron tube

klystron and electron tube both are nouns.

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

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

klystron: an electron tube used to generate or amplify electromagnetic radiation in the microwave region by velocity modulation
electron tube: electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

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

klystron (noun)	electron tube (noun)
an electron tube used to generate or amplify electromagnetic radiation in the microwave region by velocity modulation	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope