The most famous marsupial of the moment is Heidi, the cross-eyed opossum from Germany. Heidi has made headlines across the globe and has over 200,000 fans on Facebook. Enough with the cuteness, and on to a great story of language: What is the difference between possum and opossum? The answer is more complex and interesting than you might think.

The opossum received its name in the early 1600s from Captain John Smith of the Jamestown colony in Virginia. The name is derived from aposoum, a Virginia Algonquian word meaning “white beast.” The first recorded reference to the opossum in literature came in 1610 in the following passage from A True Declaration of the Estate of the Colonie in Virginia: “There are … Apossouns, in shape like to pigges.” In the late 1700s, Sir Joseph Banks, a naturalist who accompanied Captain James Cook on his first great voyage, likened a furry creature he saw in Australia to “an animal of the Opossum tribe.” The term for the ringtail marsupial that he spotted was shortened to possum. This truncation of the original term may explain why many people are surprised to learn that opossum and possum are in fact two very different marsupial species of the arboreal kind.

Possessing a furry tail, the true possum belongs to the Phalangeridae family within the Marsupialia order and is primarily found in New Guinea, Australia, Indonesia and other islands in the Pacific region. There are many varieties of possums, including Gliders and Cuscus, while the opossum is a more limited species. With their signature bare tail, the opossum is North America’s only known marsupial; this means the animal carries its young in a pouch much like the Australian kangaroo. Both the possum and the opossum are nocturnal, nomadic omnivores and live on an expansive diet that includes insects, frogs, birds, snakes and fruits. The opossum is primarily dark gray in color but some resemble cinnamon, and, as in Heidi’s case, white opossums are known to exist. The possum is primarily gray in color. The possum and the opossum are both hunted animals and possess an instinct to play dead, or “play possum” when threatened.

Whether the sharp-toothed furry critter who rustles around outside your garbage cans at night is a possum or an opossum may simply come down to where you are in the world.