1. Vacuum Tubes (or Thermionic Valves): These are glass or metal tubes that contain a vacuum and various electrodes, including a cathode, anode, and possibly a grid. They are known for their use in older electronics, especially in audio amplifiers, radios, and televisions.

2. Cathode Ray Tubes (CRTs): These are specialized vacuum tubes used in older televisions and computer monitors. They generate images by directing a beam of electrons at a phosphor-coated screen, which then emits light.

While both are electron tubes, they have distinct functionalities and applications.