This is the "Melbourne" reverse (D) which was used at Perth mints (with a dot after the last A in AUSTRALIA) and at Melbourne. The P in PENNY points to a denticle. The 2 is very curved on the down-stroke and the tail starts thin, thickening as it goes with an up-sweep at the end. The 5 shows a good serif to the top stroke. This seems to be a common coin.
The "Perth" reverse (G) was used at Perth and London mints. There is a dot after the last A in AUSTRALIA and the P in Penny points to the gap between denticles. Known as the wide 2, this coin is also fairly plentiful from my hoodling.
This example is using the "Melbourne" (D) reverse but with a dot after the A in Australia. The P in PENNY points to a denticle , the 2 is taller and has an up-sweeping tail. This is the pointed serif variety.
This coin is similar to the one above's details but has a square end on the tail of the 2, generally thought to be from a damaged die. This coin seems to be fairly scarce.
This variety is similar to the pointed serif variety but the tail of the 2 has a gradual and small taper, where the pointed serif has a more distinct upturn at the end. Wedge serif? This coin has a cud at th roo's tail, but without that it appears to be fairly scarce in my lot of Penny samples.
The Tall 2 or pointed serif variety can show the 2 lean to the left or right as in the image.