Here's a quick comparison:
* Australian Shepherd:
* Height: 18-23 inches (males), 17-21 inches (females)
* Weight: 40-70 pounds (males), 35-65 pounds (females)
* Brittany Spaniel:
* Height: 17.5-20.5 inches (males), 17-19.5 inches (females)
* Weight: 30-40 pounds (males), 25-35 pounds (females)
As you can see, the Australian Shepherd is generally taller and heavier than the Brittany Spaniel.