The entire range of electromagnetic waves, from radio waves to gamma rays, is called the electromagnetic spectrum. If both radio waves and gamma rays are part of the electromagnetic spectrum, then how are they different?

The sequence from longest wavelength (radio waves) to shortest wavelength (gamma rays) is also a sequence in energy from lowest energy to highest energy. Remember that waves transport energy from place to place. The energy carried by a radio wave is low, while the energy carried by a gamma ray is high.