We often mistake wasabi sauce and mustard sauce for the same kind. In fact, they are very different, especially in the taste, so we must pay attention to the difference.
Wasabi sauce generally appears in Japanese cuisine and is called green mustard sauce by Chinese people. Moreover, because the aroma and spicy taste of wasabi are easy to volatilize, many of them are ground on the spot in Japanese food stores, and fresh wasabi is also a slightly more expensive food.
The real mustard sauce is ground from the seeds of mustard vegetables, which is yellow, that is, the yellow mustard sauce you usually see. Now it is more common in western fast food, especially in hamburgers and hot dogs. It has a long history in China, and has been eaten since the Zhou Dynasty.