Tamari looks like soy sauce. It tastes almost like soy sauce. So isn’t tamari just a fancy word for soy sauce? No, not quite.
“Soy sauce” is a general term for a whole range of products developed in Asia. The common soy sauce sold in America is a Chinese version brewed from soy and wheat. Tamari is a Japanese soy sauce made with little or no wheat. And while both are fermented, tamari is a by-product of miso production, while Chinese soy sauce is not a by-product of anything.
The flavor of the two differs in subtle but important ways.