Linguists are always quick to point out the geographical uniformity of Australian English. Despite some stylistically and socially marked variation, there is surprisingly little in the way of regional variation in the country. When dialects come together, a kind of melting-pot effect is usual and this uniformity grew out of a blending of the original British dialects which first came into Australia; that is, from south-east England, Ireland, and Scotland. In a short period of time, all the different varieties spoken by convicts and free settlers underwent a general levelling process to produce what we now know as Australian English. Uniformity was then enhanced by the high mobility of the population during the early years. With New South Wales as the point of departure, settlement was largely by sea and the rapid spread meant the language was able to keep reasonably constant.
Non-linguists, however, are often puzzled by these claims. They will point out that Melburnians at times seem to speak a very different language. For example, a 10-ounce measure of beer in Melbourne is a pot, in Sydney a middy and in Alice Springs a ten. Melburnians are also more likely to say lacker band in place of the Australia-wide rubber band (or lacky band) and runners in place of sandshoes (typically coloured running shoes with a stripe down the side). People will also point to that round yeasty cake with pink or white icing and desiccated coconut on top - people from Melbourne (and some New Zealanders) call it a Boston Bun, but elsewhere it is a teacake or a yeast bun. Even the names of those little containers of ice cream differ - a dixie in Melbourne, elsewhere a dandy, bucket, cup or tub (of ice cream). Melbourne children are more likely to play on a slide, and those in Sydney on a slippery dip. Victorians are also more likely to say a blood nose than a bleeding nose or a bloody nose, a nature strip rather than a verge, and a three-cornered jack for that nasty little prickle with a three-cornered spine, elsewhere called a double-gee.
There are even expressions that appear confined to Melbourne; for example, busy as Bourke Street 'very busy indeed'; hook turn 'a right-hand turn made from the left side of the road when the green light becomes red' (a peculiarly Melbourne-based driving manoeuvre made necessary by the trams occupying the middle of the road); connie 'a tram conductor'; more front than Myer's 'impudent' (after the Melbourne department store Myer); the Paris end of Collins Street 'the posh tree-lined end of Collins Street between Swanston and Spring streets'; doing the Tan 'jogging track around Kings Domain and the Royal Botanic Gardens'; yarra 'mad, insane' (from the location of the old Insane Asylum at Yarra Bend'; Yarra banker 'a soapbox orator on the banks of the Yarra River'; yonnie 'a pebble'. Sometimes these Melburnisms become a part of the national lexicon; for example, double dissolution 'the simultaneous dissolution of both houses of parliament'. A number of general football terms like white maggot 'a football umpire' also have Melbourne origins.
Undoubtedly this sort of regional variation is significant for speakers. Melburnians who order scallops in a fish shop in Sydney will understandably feel cheated when, in place of the expected serve of succulent marine bivalve molluscs they are handed slices of potato dipped in batter and fried. But these sorts of differences, as interesting as they are to people, are not terribly significant when it comes to linguistic diversity. Differences in vocabulary do not make for different dialects.
Pronunciation differences are not particularly striking either. The popular claims that people can identify someone's place of origin purely on the basis of how they speak are exaggerated. Accent differences are more likely to be a matter of statistical tendency, with a certain pronunciation occurring more in one place than another. For example, Melbourne people are more likely to say pl[æ]nt with [æ] (as in 'bat') and Sydney people pl[a]nt with an [a] (as in 'cart'). Adelaide and Perth speakers are even more likely to say pl[a]nt. But, as linguists like David Bradley have shown, this is actually quite a complex variation and you do not find the vowel uniformly across words which could potentially have the same vowel; for example, grasp and clasp nearly always have [a], but plant and dance are variable. So you might find people in Melbourne saying c[æ]stle but d[a]nce and pl[a]nt. There are also very complex social and stylistic factors involved. For example, if you went to an independent school, you are more likely to say d[a]nce and pl[a]nt. And if the situation is a more formal one, the likelihood of [a] is even greater.
Certainly some of these accent differences have existed from the beginning of settlement. They evolved because of the slightly different dialect mixes in each region. For instance, the Melbourne pronunciation of words like castle as c[æ]stle represents an older pronunciation and is more likely to be found in the north of England. It is assumed that more people from the north originally settled in Melbourne. But the dialect melting-pot effect would have meant that most of these differences would have been levelled out early on. If we are searching for evidence of linguistic variation then it is rural areas that are producing the most distinctive varieties. Certainly in Australia the separation of urban and rural communities seems to inspire the richest regional diversity and we can find some significant differences, particularly with respect to speed and also broadness of accent. People in Melbourne tend to speak faster than those in rural Victoria of the same socio-economic background. You will find a greater proportion of broad speakers in rural Victoria, too. But again these differences are matters of accent not dialect. Accent refers to the pronunciation a speaker uses. Dialect refers to a speaker's vocabulary and grammar. As yet we cannot claim to have regional dialects.
Different ethnic mixes have contributed significantly to diversity. In Melbourne, for example, the Italian and Greek communities are beginning to add a vibrant, new and socially relevant aspect to Melbourne English. The fact that there is no single prestige regional variety of the language in the country means that, if groups want to be defined regionally, varieties are freer to go their separate ways.