Stole this from elsewhere…
Consumers have long been confused about the difference between these fruit and the fact is that while they are the same species Carica papaya, the fruit known as papaya looks and tastes quite different to the fruit known as papaw.
To make things easier for consumers the agreed understanding in the Australian industry is that the red-fleshed sweeter fruit is called red papaya, while the yellow-fleshed fruit is called yellow papaw.
American pawpaw (note the different spelling) on the other hand is an entirely different fruit not related to the tropical Carica papaya from which Australian red papaya and yellow papaw come. American pawpaw is also known as ‘poor man’s banana’ and is the fruit of the Asimina triloba tree.
To complicate things further, there’s also green papaya, which is either red papaya or yellow papaw picked green. Green papaya is a sought after ingredient in Asian cuisine and is eaten as a vegetable.