Both the AM waves and FM waves are part of electromagnetic spectrum band. Both fall under radio waves, so they have same physical nature Both AM and FM waves have the same speed when they travel in the same medium. AM waves are amplitude modulated waves whereas FM waves are frequency modulated.
same medium, and they both have the same physical
nature, since they're all electromagnetic radiation.
Many point-to-point radio systems use AM and FM at the same time
on the same signal, in order to carry more information on the signal.