Hey lizardjasper, seems like you're copping a bit of flack from your fellow QLD'ers!
Mate, the only dumb question there is, is the one you don't ask. Good on you for wanting to find out. Here goes, hopefully, it'll help and it's not too long-winded. Will try to keep it simple.
All the snakes you mentioned belong essentially to two genus's (sorry, probably be a typo there??): Antaresia & Morelia, or more commonly: Children's python family & Carpet python family. I have listed them for you as follows:
Genus: Antaresia - contains 4 small to very small species:
1. Antaresia childreni - Children's Python, grows to about 1m or so,
2. Antaresia maculosa - Spotted Python - grows to about 1m or so as well,
3. Antaresia perthensis - Pygmy Python - only grows to about 61cm, is the world's smallest python, and
4. Antaresia stimsoni - Stimson's Python, grows to about 90cm.
Captive bred Children's Pythons are generally very calm, placid and "friendly" snakes, which make them ideal as a beginner, first snake. Easy to keep and don't grow too big so won't swallow you whilst you're sleeping! lol
Genus: Morelia - contains 5 moderate to very large species:
1. Morelia carinata - Rough-scaled Python - grows to about 2m,
2. Morelia kinghorni - Aust. Scrub Python (scrubbies) - Australia's largest snake, grows to about 5m+
3. Morelia oenpelliensis - Oenpelli Rock Python - grows to about 4.3m,
4. Morelia spilota - Carpet Python; Diamond Python - Sub-species include: Centralian Carpet (Bredli), Top End Carpet, Eastern Carpet, Jungle Carpet, Murray Darling Carpet & Western Carpet. Carpets grow to 2.5m or thereabouts in general.
5. Morelia viridis - Green Tree Python (GTP), grows to about 1.5m
So, the difference I guess is their genus, and also their different species and sub-species. There are the physical differences like size, colours and patterns but I won't go there because it's best for you to buy a book if you really want to know.
Anything else specific you wanted to know, I am sure you'll find lots of useful info here on this site by searching the posts and forum. Good luck with it all, hope that helps.