In a vacuum of space unaffected by any gravitational curvature or any kind of energy, the speed of an electromagnetic wave is c, 3*10^8 m/s. Radio frequency and infrared waves, have been proven by experiment to travel at the speed c.
There are two fundamental properties to any transverse wave. They are wavelength and frequency. Since the speed of an electromagnetic wave, a transverse wave, is always c, the frequency and wavelength vary depending on the type of wave we are dealing with but their products are always the same, the speed of light.
That is, (Frequency of Radio Wave)(Wavelength of Radio Wave)=(Frequency of Infrared Wave)(Wavelength of Infrared Wave)=The Speed of an Electromagnetic Wave, c.
That being said, an infrared wave and a radio wave differ from each other based on their frequency and wavelength.