Adult mice, including their tail, are around 7 ½ inches long; while adult rats, including their tail, grow up to 18 inches long.
Mice have thin tails with a bit of hair; while rats have a thicker, scaly tail without hair.
Mice snouts are triangular, while rat snouts are blunter and rounder.
Mice eyes appear larger than the rest of their face, while rat eyes appear smaller or beady.
Mice droppings are roughly 1/4-inch-long with pointed ends, while rat droppings are around 3/4-inch-long with blunt ends.