I just found out today that a possum and an opossum are two different animals. I just thought people who were too lazy to say opossum used possum instead. Nope. They are both marsupials, but possums are native to Australia and New Guinea, among other places, while opossums are native to the Americas. That doesn't mean you can't use possum when you mean opossum, but just know that they are different animals.
