Light-emitting diodes are more commonly used, and the positive and negative electrodes are easy to distinguish. The long pin is positive and the short pin is negative.
When the pins are the same, the very small metal in the LED tube body is the positive electrode, and the large one is the negative electrode.
SMD light-emitting diodes generally have a small bump to distinguish positive and negative poles, with special marks as negative electrodes and no special marks as positive poles.