electron tube vs thermionic vacuum tube

electron tube and thermionic vacuum tube both are nouns.

Word	Noun	Adjective	Verb	Adverb
electron tube	Yes	No	No	No
thermionic vacuum tube	Yes	No	No	No

As nouns, electron tube and thermionic vacuum tube are synonyms defined as:

electron tube and thermionic vacuum tube: electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

Other synonyms of electron tube include thermionic tube, thermionic valve, tube, vacuum tube.

electron tube (noun)	thermionic vacuum tube (noun)
electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope	electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope