Green is the color that our eyes see the best. It should still show up reasonably on a brown house. It will not be the same as on a lighter colored surface, but it should still work as long as there is not too much light from other sources such as a street light. The red however will probably wash out and not be very visible as the two colors are too close in tint.
Just like how a flashlight will reflect less on a dark color versus a light color.
For more info check out our Ultimate Guide to Laser Xmas Lights – http://laserchristmaslightshq.com/ultimate-guide-christmas-laser-lights/
Or our Holiday Projector Guide explaining the five highest quality and most affordable projectors on the market – http://laserchristmaslightshq.com/best-laser-light-projectors/