Wasabi vs horseradish sauce?!
Answers: What is the differnce between wasabi and horseradish sauce, besides the color?
They are not the same!
WASABI:
Wasabi is a plant grown primarily in Japan with nascent horticulture now in the Pacific northwest of the US. The root (technically a rhizome) is ground and used in foods to add spiciness and flavor. It is a difficult plant to grow, requiring a rocky stream or riverbed and the proper mix of nutrients, and is therefore a somewhat rare commodity. Wasabi, traditionally reserved for sushi and noodles, is now being incorporated into a plethora of foods; however, 'wasabi' flavored items are not always actually wasabi flavored.
Real wasabi has a fruity and vegetal fragrance, with a spiciness that does not linger and serves to enhance the flavor of the fish. It has a bouquet and sweetness that stimulates the palate with balanced heat. It does not hit with the intensity that fake wasabi does, and the spiciness quickly dissipates into the sweet vegetal flavor that is a perfect companion to sushi. The hotness of wasabi is experienced more in the sinus than the tongue and is often an acquired taste.
**************************************...
HORSERADISH:
The horseradish root itself has hardly any aroma. When cut or grated, however, enzymes from the damaged plant cells break down sinigrin (a glucosinolate) to produce allyl isothiocyanate (mustard oil), which irritates the sinuses and eyes. Once grated, if not used immediately or mixed in vinegar, the root darkens and loses its pungency and becomes unpleasantly bitter when exposed to air and heat.
Cooks use the terms 'horseradish' or 'prepared horseradish' to refer to the grated root of the horseradish plant mixed with vinegar. Prepared horseradish is white to creamy-beige in color. It will keep for months refrigerated but eventually will start to darken, indicating it is losing flavor and should be replaced. The leaves of the plant, which while edible aren't commonly eaten, are referred to as 'horseradish greens.' Although technically a vegetable, horseradish is generally treated as a condiment or ingredient.
Horseradish dyed green is often substituted for the more expensive wasabi traditionally served with sushi, even in Japan. The Japanese botanical name for horseradish is seiyōwasabi (セイヨウワサビ, 西洋山葵, seiyōwasabi?), or "Western wasabi".
If you're referring to the wasabi you get in most Japanese restaurants (in the USA), then there is no real difference since it's just basically horseradish that's been dyed green.