What is the difference between a Shiba Inu and an Akita Inu?

I'm curious to know, what are the main differences between a Shiba Inu and an Akita Inu? Are they just variations of the same breed, or do they have distinct characteristics that set them apart? Are there any notable differences in their physical appearance, temperament, or origins? I'm interested in understanding the key factors that differentiate these two breeds of dogs.