Photon

Numerous scientists contributed to the discovery of this concept, but the key was introduced by Albert Einstein in 1905. This concept was used to support the experiment of the photoelectric effect to prove that light could be as a wave too. Then this name photon was given 21 years later, in 1926 by Gilbert N. Lewis.

Yes, they travel in a vacuum at the speed of light and can never be in still position. This is because they do not have any mass to do so and will not exist only if not in motion.

The key difference lies in not their spelling but the properties they possess. Protons are positively charged particles which revolve around the nucleus of an atom and have a specific mass. Whereas, photons don't have any mass and are responsible for carrying out electromagnetic radiation. They travel free without any restriction.