From head to tail mice are smaller than rats by several inches. Mice also have smaller droppings (6 mm vs 12 mm) and gnaw marks (2 mm vs 4 mm) than rats.  Mice have larger ears and pointy or triangular noises whereas rats have small ears and blunt noses. Both have long tails but mice have thin, hairy tails. Rats on the other hand have thick, scaly tails devoid of hair.