Microwaves and radio waves are both used for communication purposes. Microwaves have a higher frequency, and therefore a smaller wavelength. Because of this, microwaves can travel through the Earth's atmosphere, reach satellites and be used in mobile phone communication across the world.
Radio waves have a much lower frequency. Due to the Earth's curvature, there is blockage from one radio station to the next. This is overcome using Diffraction. As the wavelength is so long, radio waves are diffracted by the Earth's atmosphere, round the curvature to the radio station.