kangaroos and koalas

Koalas are sometimes called koala bears, which is wrong, no matter how cuddly teddy bear-ish they look.  They are marsupials, which bears are certainly not.  Kangaroos however, are, so koalas and kangaroos are related.

There are four species of kangaroos - Eastern Grey, Western Grey, Red, and Antilopine.

The Antilopine kangaroos are found primarily in the north. The Reds are the largest.  There are way more Eastern Greys than Western Greys.  Both of these stamps feature Eastern Greys.