vacuum tube vs thermionic vacuum tube

vacuum tube and thermionic vacuum tube both are nouns.

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

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

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

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

vacuum 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