"There are only just over a dozen albino alligators in the world and this one (top picture) lives at Gatorland in Orlando.
Her name is Pearl. She's about 10-years-old, 7 1/2 feet long and 105 pounds." source
If you've seen a white alligator it's unlikely that you've seen a true albino and more likely it was just leucistic (pictured below), meaning it had reduced melanin (and other pigments), but not totally albino. A good tell is usually the eye color. (source r/atreides)