Basically the Liberals are like the Tories and Nationals are like the Uber-Tories and they're part of what is known as the Coalition (but are basically the same party) - they're in government and are massive climate-change denying c***s.
Labor is like well Labour, and the only real opposition to the Coalition, and are slightly leading in the polls.
There's Pauline Hansen and her One Nation Party - which is like the BNP (she's a fucking psycho) and Fatty Coal Magnate Clive Palmer and his United Australia Party - which is like UKIP. There's also Katter's Australia which is fucking mental - he's famous for this clip
There's also the Greens - which compete with Labor in some seats, and are about as relevant as the Greens over here.