The flight is just over an hour long in actual time (remember that Melbourne is half an hour ahead of Adelaide's time.)
451 miles
If it is 3pm in Adelaide, it is 3:30pm in Melbourne.
Good traffic, about 7 hours.
Adelaide, the capital of South Australia, is northwest of Melbourne.
9:00 Adelaide is half an hour Behind Melbourne
The driving distance between Melbourne and Adelaide is 725km (450 miles), and the journey takes around 9 hours to travel, without breaks. It is a full day's journey.
Adelaide is closer.
There are several major routes from Melbourne to Adelaide, but the most logical is the Princes Highway.
From Adelaide to Melbourne by air is a distance of 655 km, or 407 miles.
I believe it has something to do with the general wind direction. It tends, as far as I know, to progress from west to east, so when a plane is flying west (to Melbourne), the plane is flying against the wind, and will take longer. When the plane is flying east (i.e. from Adelaide to Melbourne), it is flying with the wind and thus doesn't take as long. The same thing occurs flying from Melbourne to New Zealand - it takes less time to reach New Zealand than it does to return - the difference being roughly an hour.
There are 406.61 air miles between Adelaide and Melbourne and there are 451.31 by road.