In a vacuum, photons and electrons both travel at the same maximum speed, which is the speed of light, denoted by the symbol 'c.' According to the theory of relativity, the speed of light in a vacuum is constant and is approximately 299,792,458 meters per second.
Photons, being massless particles, always travel at the speed of light. On the other hand, electrons have mass and can travel at speeds below the speed of light. In practice, electrons can be accelerated to high speeds but will never reach or exceed the speed of light unless they are massless.
Therefore, in terms of maximum achievable speed, photons travel at the fastest speed, while electrons (with mass) can only reach speeds that are lower than the speed of light.