Five ways you can tell you are in Melbourne, not Sydney.

Sally of Sydney Daily Photo has a sequence of posts on the differences between Melbourne and Sydney.

Trams
Hook turns
Fences
Train stations
Level crossings

Of the cities I have been to, Sydney and Melbourne are two of my favourites. Disclaimer, I am a sydneysider.
More reading: Tags, Sydney, Melbourne
Cam Riley: South Sea Republic. Freedom, liberty, equity and an Australian Republic.