thermionic vacuum tube vs electron tube

thermionic vacuum tube and electron tube both are nouns.

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

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

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

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

thermionic vacuum tube (noun)	electron 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