How bad does it get? hehe

From my POV, these American ears hear alot of differences
but inside the same country!

Australian English is not the same throughout the entire country -
there are dialects, slight modifications, depending on where the speaker was raised.
An Australian from Darwin does not sound exactly like one from Perth or Sydney.

The same goes for NZ.
The further South you go, the more the accent and inflection changes.

But I'm not picking on either camp -
it's the same in the USA.
Listen to a native New Yorker, someone from Arkansas, and one each from Texas, Maine, and California
and you will hear five different variations on the same language.

I don't think you should ask 'how bad does it get?'
I don't feel it's a bad thing at all.
Life would be pretty boring if we all sounded the same.
Viva la difference!
:-)

Most of the difference in accents is to do with pronunciation of vowels and Rs. Vowels are defined by the tongue position as they are sounded. There is an almost infinite number of possible positions and therefore an almost infinite number of possible vowels.

The front vowels are those sounded with the tongue towards the front of the mouth and these are the vowels in the words "pat", "pet", "pit" and "peat". The other descriptor of tongue position is height. "pat" has a low front vowel while "pit" has a high front vowel.

When we sound vowels, the tongue moves to a position within the range of sounds we hear as the appropriate vowel. In New Zealand, there is a shift in the central position of most of the front vowels. The tongue moves closer to the next vowel. New Zealanders don't go all the way but sufficiently for us to hear their vowels differently. "pat" gets close to "pet"; "pet gets close to "pit" and the high front vowel in "pit" moves back towards the high mid vowel in "pert".

It is a small shift in the mean position for sounding the vowels but it makes quite a difference to the non-Kiwi ear.

The Aussies speak funny they say feesh and cheeps.

Its almost as though the Scottish accent has had a big influence in Un Zud (NZ). Its not that different really, but if you want a laugh ask one to say check-in and chicken. Then try to tell the difference :-)

the difference is the kiwis sound like they have speech impediments compared to the aussie slang and swear words

this is a kiwi saying (hey bro) - what the fukk bro bullsh!t trying to be like the african americans and the aboriginals

another saying (do you want some fush and chups) - for goodness sake speak english will yas

The first difference is that there is no such thing as Ozzie English.
It's AUSSIE.

If you want to talk like us (that is - shortening everything) then please do call us Aussies (Australian) and "Aust" - as in - "coming to Aust".

As far as kiwi pronunciation - well, they always love thier "fush and chups".

Seexes and Seevens

Firstly it's not "ozzie" , it's "Aussie!". Kiwis pronounce all their vowels very strangely- eg- fish and chips sounds like fush and chups.