http://www.ratbehavior.org/RatsMice.htm
What do the terms rat and mouse mean?
Rat and mouse are actually not scientific classifications. These words are common names for rodents that look alike to the casual eye.
Rat is used to describe medium-sized rodents with long thin tails. There are many species of rodent that are called rats -- kangaroo rats, cotton rats, Norway rats, black rats, African pouched rats, naked mole rats, wood rats, pack rats, Polynesian rats, and many others. These different rodent species may not be closely related to each other at all!
Mouse is used to describe tiny, sparrow-sized rodents with long thin tails. As with rats, there are many species of rodents called mice which may or may not be closely related to each other: house mice, field mice, deer mice, smoky mice, spiny mice, and dormice are all called mice.
So, which rats and mice are you talking about? Generally, people are referring to the domestic or pest rats and mice, which means Norway rats (Rattus norvegicus), black rats (Rattus rattus), and house mice (Mus musculus).
****Mouse 係可愛d (如 mickey mouse 唔係 mickey rat)
****rat 係可怕do既老鼠