Belong, Boost and woolworths (along with many others) uses the Telstra mobile network but I heard it uses MVNO so the coverage is not quite the same as signing up directly with Telstra.
How much difference is the coverage and are there any other limitations?
Boost is the only MVNO that has 100% of the Telstra network. The others have the wholesale network, which is fine until you head outside of the main cities. My family have Aldi (wholesale) and I have Boost, I get good signal in places where they struggle.