A rat is larger than a mouse and can weigh up to 0.5 kilograms (1 pound). The Norway rat and the roof rat look similar, but their habits are different. The Norway rat builds elaborate systems of tunnels and burrows at ground level. It prefers damp areas like crawl spaces or building perimeters. The roof rat is an agile climber and prefers to live in trees, vines, and other dense vegetation. It will infest attics, rafters, or roofs, and upper stories of buildings.
Knowing the type of pest you have can help you figure out the best approach to controlling them. (For example, a rat trap is too large to capture a mouse.)
Mice and rats are carriers of disease, and can damage property. The deer mouse is the most common carrier of the deadly hantavirus.