A feature common to triode tubes and transistors is that both:

Triode vacuum tubes and transistors are both fundamental active electronic components whose primary shared function is their ability to amplify electrical signals. A small input signal applied to their respective control elements (the grid in a triode or the base/gate in a transistor) modulates a much larger current flowing through the device. While they achieve amplification, their physical operating principles are quite different. Distractors like using 'heat to cause electron movement' (thermionic emission) or having electrons 'drifting through a vacuum' are characteristics unique to vacuum tubes. Transistors are solid-state devices that do not rely on heated filaments or vacuum enclosures.