Deer mice have brown or gray fur with white bellies and tail bottoms. A deer mouse’s tail is approximately the same length as its body. Deer mice have hind legs that are longer than the forelegs. Deer mice have larger eyes and ears as compared to house mice, which is often the most reliable method for differentiating between the two mice species. House mice typically have gray fur; some have brown shading along their backs or undersides. House mice are about 8 cm in length, have long tails that are partially covered in fur, and have short hind legs.