Rectifying tube and Vacuum tube

Rectifying tube noun - A thermionic tube having two electrodes; used as a rectifier.

Vacuum tube and rectifying tube are semantically related. In some cases you can use "Vacuum tube" instead a noun phrase "Rectifying tube".

Vacuum tube noun - Electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope.

Rectifying tube and vacuum tube are semantically related. Sometimes you can replace phrase "Rectifying tube" with "Vacuum tube", this phrases are similar.