Kriol is not at all at all "a form of aboriginal english". It is a close relative of Tok Pisin and Bislama, however, despite substantial lexical borrowings, it bears essentially no gramatical relation to English.
Aboriginal english, on the other hand is a distinct variety of English (in the same sense that, British, American or Austrlain Englishes are varieties), with many interesting pragmatic subtilties that get in the way of clear communication between speakers of Aboriginal and Australian english. The wonderful Diana Eades has written quite a bit about the practical differences between Aboriginal and Australian Englishes in the hope of fostering beter communication, however she stopped after she noticed one of her books on the desk of a lawyer for the prosecution one day who was using her research to actively provide a false impression to the jury.
A good example of the frequent assumption that Kriol and Aboriginal English are bastardised versions of English is the analysis of the morpheme '-fella' as a borrowing from English 'fellow'. As in blackfella, whitefella. If you stop and think about this it is actually quite strange, why of all the English words for person would fellow have been borrowed?
Excuse me, my good fellow, would your be so kind as to drink this water. It's top stuff I just got from Myall Creek
Surely 'man' would be the most obvious word to borrow instead. But what's more, why borrow a word for 'person'. Do we seriously suposse that indigenous Australians didn't have a word, or rather a whole range of words to deal with the concept person?
Instead the best bet (as of a few years ago at least), was that it is was originally from Eora, the now extinct language of much of the Sydney region and was is reconstructed as something along the lines of '-pela' (going off memory here), a suffix added to an adjective to mark that the adjective is modfiying the noun. and spread as the English/Indig contact jargon/pidgin spread with colonisation. It can still be found in Tok Pisin '-pela', and Bislama and Pijin '-fala'. It is was then borrowed from these creoles into Aboriginal English to become its most famous word (blackfella - n. Indigenous Australian).