There are 5 basic sets of the Threatened species stamps. And countless reprints.
1) Sheet stamps perf 14. The 1koala reprint is on CPL paper but I have no idea what that is & my catalogue doesn't elucidate
That's the easy one, now the fun begins.
ALL stamps not perf 14 are self-stick coil/booklet stamps & there are four sets of these, all with helecon coatings, we'll start with the two easy ones. If you don't have the correct light for these all is not lost. You can see the coatings by holding the stamp up to a light at a shallow angle - move the stamp from horizontal with your eye, to a slight angle.
2) Vertical band covering the right half of the stamp. You can make this out on the two left scans of the wallaby & pygmy possum
3) Horizontal bands on the upper & lower white areas plus helecon in the shape of the animal of the stamp. Don't get confused with the last two groups which are all-over helecon. With the all-over you're going to see a difference in printing between the animal part & the upper & lower areas, but the horizontal bands/animal really jumps out particularly looking at it at an angle.
If you've got a typically perfed coil stamp & it shows no bands or animal coating, then you've got an all-over coating
4) All-over helecon coating, letter-press coarse printing
5) All-over helecon coating, litho fine printing
You're going to need a good magnifying glass for this, x15 should be fine. The printing dots in the coarse version are much larger than in the fine.
Here's two samples, coarse on the left, fine on the right
Around this period I had access to several offices which saved me their clippings, wonderful stuff. I gave up on Australia in 1994, just too much wallpaper. I haven't looked at this stuff for years but I notice that I have one stamp mis-labelled, it's replacement is drying even as we speak