Sounds like a funny question, but was he?
Responses (2)
Mice have smaller heads and larger ears and eyes relative to the head compared with rats. Both are rodents but they have some genetic differences — rats have 21 pairs of chromosomes and mice have 20 chromosomal pairs. The animals are often identified by the size of feces. Rats tend to have a slightly longer life span compared with mice.
SOURCE: www.diffen.com/difference/Mouse_vs_Rat