Glow lamp and Gas-discharge tube

Glow lamp noun - A gas-discharge tube with a hot cathode; used in stroboscopes.

Gas-discharge tube and glow lamp are semantically related. In some cases you can use "Gas-discharge tube" instead a noun phrase "Glow lamp".

Gas-discharge tube noun - A tube in which an electric discharge takes place through a gas.

Glow lamp and gas-discharge tube are semantically related. Sometimes you can replace phrase "Glow lamp" with "Gas-discharge tube", this phrases are similar.