By now, you should clearly understand the similarities and differences between soy sauce and thick soy sauce as it all comes down to their purpose. Light soy sauce is for salty flavor, dark soy sauce is for rich color, and thick soy sauce is for a sweet, syrupy glaze.
Thus, if you learn the art of using these sauces with care, you will open your kitchen to an entire new world of flavors. Enjoy cooking!