What is the difference between 'Coolie' and 'Koolie'?
Preference.
For the most part from what I've been able to see some breeders call them German Coolies because that's what they grew up calling them or they got their dogs from a breeder who called their dogs that. Same goes for the Australian Koolie breeders. I've heard some people try and say that German Coolie is the older real line but other kennels that are as old or older call them Australian Koolies so I don't give that much credence.
There are people who insist there is a difference like Ida in Texas who says she breeds German Coolies and not Australian Koolies. But honestly, from what I can tell is there are certain kennels and lines that have distinct looks to them and they call their dogs one or the other and that's the biggest difference. So her dogs might be different but most breeders in Australia see them as a Coolie is a Koolie is a Coolie is a Koolie.
Like I said, Traveler's dad is from an outcross. Toolalla (Richie) has grown up calling his dogs Australian Koolies but quite often outcrosses to a kennel called Borahview Coolies. And that's not uncommon.
So yeah, my opinion is same dog.