Green’s Dictionary of Slang

(Aus./Irish/N.Z.) the difference.

1908		Bulletin (Sydney) 5 Nov. 39/2: ‘You’re all right,’ she said [...]. ‘You’ve got your senses back. Do you know the differ., eh?’ / ‘There isn’t any differ., with some folk,’ I said, feebly. ‘But I do know that I’m very hungry.’.
1918		K.F. Purdon Dinny on the Doorstep 196: Sure, how was I to know the differ!
1995		P. O’Keeffe Down Cobbled Streets, A Liberties Childhood 75: D’ye think they’d know the differ if we went to one of the shops and brought back shop milk?
2003		McGill Reed Dict. of N.Z. Sl.