Short answer: tamari sauce is a type of soy sauce from Japan. It contains very little or no wheat. Long answer - complete guide to soy sauce.
What Is Tamari and How Is It Different From Soy Sauce?
Tamari vs Soy Sauce: What's the Difference?
A Guide to Different Types of Soy Sauce - Uwajimaya
What Is Tamari?, Cooking School
Soy Sauce Vs. Tamari: What's The Difference?
What's the Difference Between Soy Sauce, Shoyu, and Tamari? - Eater
Are Soy Sauce & Tamari Low FODMAP? - FODMAP Everyday
Soy Sauce, Tamari, Liquid Aminos: What's the Difference? - Forks
Tamari vs. Soy Sauce (& Coconut Aminos?) - Hungry Huy
What's the Difference Between Tamari vs Soy Sauce?
Tamari vs Soy Sauce, Cooking School
Tamari vs. Soy Sauce (& Coconut Aminos?) - Hungry Huy