White has no hue; it is the color we see when we look at light which contains all the wavelengths of the visible spectrum, at full brightness and without absorption. Substances appear white because their surfaces reflect back most of the light that strikes them.*
Green is a combination of two primary colors; blue and yellow. The green in plants is created by photosynthesis; the process in which light is absorbed by plant proteins that contain chlorophyll pigments. This chemical reaction provides the energy a plant requires to live. *
Side by side, green and white are stunning. Here are some examples from my gardens.