thermionic valve vs vacuum tube

thermionic valve and vacuum tube both are nouns.

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

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

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

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

thermionic valve (noun)	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