thermionic valve vs thermionic vacuum tube

thermionic valve and thermionic vacuum tube both are nouns.

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

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

thermionic valve and thermionic 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, tube, vacuum tube.

thermionic valve (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