From Bushwalk Australia

en·dem·ic {en'demik} This adjective is used to describe a plant or animal that is restricted to a certain area or certain country. So a plant that is endemic to Tasmania, only naturally grows in Tasmania, and no where else.

"Native" (plant or animal) is a term used to indicate that a species occurs naturally in a given area or country. Some plants that are "native" to Australia also occur naturally in other countries (i.e. are "native" in those countries too). If the natural distribution is limited to just Australia, then the preferred term is endemic.