is a specific kind of: squirrel.

is a broader term that covers: cat squirrel, eastern gray squirrel, eastern grey squirrel, Sciurus carolinensis | Sciurus griseus, western gray squirrel, western grey squirrel | eastern fox squirrel, fox squirrel, Sciurus niger | black squirrel | cat squirrel, red squirrel, Sciurus vulgaris | American red squirrel, red squirrel, Sciurus hudsonicus, spruce squirrel, Tamiasciurus hudsonicus | chickeree, Douglas squirrel, Tamiasciurus douglasi.

is a member of: genus Sciurus, Sciurus.