Im really not sure if you wanted the taxonomic difference or like how to keep them, so heres some info and if thats not what ur looking for, i apologize
As of now, they are all 3 subspecies of each other, with the diamond being the nominate race
diamond python - Morelia spilota spilota
coastal carpet - Morelia spilota mcdowelli
jungle carpet - Morelia spilota cheynei
Thats how it is now, but i belive they will probably be reclassified into all seperate species soon.
The diamond is typicaly black with a spot of yellow in the centre of each scute, while the other two have more banded patterns....the coastal is typically larger than the jungle and less vibrant
if you are really interested in them, read this.
http://www.pythons.net/australia/carpet/
good luck