There are over 70 species of mice and rats widely distributed across North America. The house mouse (Mus musculus) and the Norway rat (Rattus norvegicus) species are in the Muridae family, which is the largest family of rodents and mammals in the world.
House mouse: Small head, small feet, pointed snout, large ears with some hair. These mice have a light brown body with some gray shading and a dark tail. Adults weigh 0.5 ounces (15 grams). The mice droppings are shaped like rods.
Norway rat: Heavy and thick body, blunt snout, and short ears with dark hair. These rats have a brown body with black shading and a shaggy coat. Their tails are dark on top and pale underneath. Adults weigh 11 ounces (300 grams). Their droppings are shaped like capsules.