An object that appears white is reflecting all the energy within the visible part of the electromagnetic spectrum that falls onto it. All objects do not necessarily reflect the same amount of light. The same object can change its reflectance over time. While we may be able to discern different shades of green between plants, the DMSV can tell apart different shades of blue, green, red, and infrared. This extra information makes telling plant types, from aerial photographs, much easier.
Light travels in waves.
The wavelength is defined as the distance between the peaks of two waves. The greater the wavelength of light, the smaller the energy being carried by that wavelength. Thus, infrared and red wavelengths carry less energy than blue and green light. The wavelength of light also affects its scattering properties. The haze you might see from a plane, as you look to the ground, is most commonly caused by the scattering of short wavelength light, particularly blue.