Rats and mice are close cousins. This means that they share a lot in common. However, there are lots of differences that set the cousins apart from each other. Their physical appearance, for instance, can be used to distinguish rats from mice. Rats are relatively bigger in size than their close relatives; on their part, adult rats weigh 11 ounces (300 grams) while mice weigh only 0.5 ounces (15 grams). In total length, including head and tail, rats can measure up to 18 inches while mice measure half of this, only 9 inches.
Other physical characteristics that distinguish the pests are the length of the tail in relation to their body size, the appearance of the eyes and ears, and the shape of the head and snout. On their part, rats have a thick, long tail that is longer than the body. Mice, on the other hand, have a relatively thin tail that is less than body length. Additionally, rats have small eyes while the eyes of mice are large and prominent. As far as ears are concerned, those of the rats are thick, opaque, and small relative to the head size while the ears of mice are large relative to the head size. The head of a rat is heavy and chunky while that of a mouse is small, sharp, and triangular with pointed muzzles.
It is also possible to use the habits exhibited by the rodents to distinguish them. While rats live indoors, outdoors, and in sewers, mice live indoors and outdoors but they rarely live in sewers. On their part, rats are omnivorous (meaning they eat almost everything including meat) and drink water regularly. Conversely, mice are nibbles and prefer cereals (but may eat a variety of foods). Mice can go for a long time without water. While rats have a life expectancy of 9 to 18 months, mice can live only up to 12 months.