The SASR's primary purpose is to train militia and guerrilla fighters and fight along side them, similar to the way US Green Berets trained the Montagnard's in Vietnam. They are also in my opinion the best for LRP's and infiltration.

The Commandos are more suited to small battles, ambushes and counter-terrorism tactics.

The RAN Clearance Divers are very similar to the US Navy SEAL's, they are explosives, shore assaults and ship boarding experts. They often fought alongside the Commandos in Afghanistan due to the 2 having similar skill sets.

Commandos are Australia's go-to for counter terrorism ops because of their particular skill set and their larger numbers.

No unit is "better" or "worse" than the others as they are all flexible and have cross-training programs and often see combat together. If a situation requires Australia's SF to attend, at least 2 of them will be there.