Aside from business, the two main candidates are separated by their views on same-sex marriage. Rudd is firmly for it, Abbott, a former Catholic seminarian, insists that marriage should be between a man and a woman.
However they're much closer on the issue of asylum seekers. Both main parties advocate sending people who arrive by boat to offshore processing centers where most, if not all, will be potentially resettled if found to be refugees.
There are other options for Australian voters. The Greens Party is the strongest of a number of smaller parties outside the two top. And then there are the newer upstarts; groups fronted by recognizable names who are vying for a Senate seat.
WikiLeaks founder Julian Assange is conducting a long-distance election campaign from the Ecuadorean Embassy in London, where he's been holed-up for fear of arrest and extradition. However, in recent weeks, his new WikiLeaks Party has been hit by a number of resignations, weakening its stance.
And Clive Palmer, the mining magnate perhaps best known outside Australia for his plans to build a replica of the Titanic, is also seeking votes for a place in the Senate on behalf of his Palmer United Party.
Polls opened at 8 a.m. Saturday (6 p.m. ET Friday) and they should close at 6 p.m. local time, with the results are expected soon after.