It is actually quite easy to tell the difference. Firstly: as an adult the Akita is much taller than the Shiba Inu. Secondly: The Akita’s coat is also more fluffy than the Shiba Inu’s. The Shiba Inu’s coat is harder and shorter. The Shiba Inu is stiffer and shorter. Third: The Akita has a wider mouth and thicker ears, while the Shiba Inu has a pointed mouth and thinner ears.
