Differences in Appearance The difference in mice and rat appearances and behaviors helps homeowners determine which pests are infesting their property. Size is the most notable physical difference between mice and rats. While rats weigh in excess of 18 ounces and grow nearly 20 inches long, mice often weigh approximately one ounce and rarely exceed 8 inches in length. The shape of the rodents' head also helps determine if mice or rats are present. Mice tend to have triangularly shaped heads with pointed muzzles, while rats have blunted snouts. Finally, mice have large ears, prominent eyes, and thin tails, whereas rats have small ears, tiny eyes, and thick tails. Differences in Behavior Mice and rats tend to behave differently in homes. Mouse presence is often accompanied by a musky scent that's absent in rat infestations. The existence of rats in homes is typically followed by grease stains along walls and floors. Additionally, while both rodents produce an excessive amount of droppings, mouse feces are smaller and spread out, while rat excrement is larger and found piled together. Need for Removal from Homes Despite all their differences, rats and mice cause the same kind of damages when they infest homes. Since they must both gnaw on objects to keep their front teeth at a manageable length, the rodents cause structural damage and put homes at risk of electrical fire. Rats and mice also carry a number of diseases and contaminate stores of food and water supplies. As such, homeowners dealing with infestations of either rodent should contact local pest control specialists immediately. The professionals at Critter Control identify which rodent is causing problems and then eliminate them humanely and effectively.