Size
The Australian Shepherd is a little larger on average: about 24 kg (52 lb) as an adult, against 19 kg (43 lb) for the Australian Cattle Dog.
Grooming
The Australian Shepherd needs more grooming, brushing a few times a week, where the Australian Cattle Dog needs a brush once a week.
Temperament
They differ most on independence (Australian Cattle Dog: cooperative, with its own ideas; Australian Shepherd: keen to work with you) and on prey drive (Australian Cattle Dog: likely to chase small pets; Australian Shepherd: chases; needs managing).
Alike
Both are rated the same on loyalty: sticks close to its people.