A compound called allyl isothiocyanate which is an organic chemical compound found in the plant is what gives wasabi it's kick.
It's the same compound that is also found in mustard and horseradish from the Brassicaceae plant family.
The difference between wasabi and real wasabi is that the real wasabi is made from the wasabi plant and most other wasabi that is sold in stores and restaurants is made using horseradish, vinegar, green food dye and vinegar.
Real wasabi is more expensive as it's hard to grow and so it's often replaced with easier to grow and cheaper substitutes.
Wasabi is not as hot as horseradish although both wasabi and horseradish are spicy and do release compounds that are volatile when cut or grated.
Wasabi has a milder pungency taste and a sweeter aftertaste than horseradish does.
Horseradish is more spicy than wasabi.
Real wasabi is not very spicy although face wasabi is more spicy than real wasabi.
Real wasabi instead of being very spicy has a gentle spiciness to it that fades quickly.
Also real wasabi has a complex flavor that also has a fresh aroma, sweet undertones and a spicy kick to it that also fades quick and can be described as aromatic and fragrant.
Fake wasabi is just dyed horseradish as the majority of wasabi paste that is sold outside of Japan is made out of regular horseradish root and green food coloring is added.
Real wasabi is made from the wasabi plant known as the Wasabia Japonica and is much harder to grow and more expensive.
So most of the wasabi that is bought and sold outside of Japan is just dyed horseradish and not real wasabi.
Real wasabi has a more delicate flavor when compared to horseradish and is often only found in high quality sushi restaurants.
Most commercially produced wasabi paste is colored with food dye to mimic the green color of real wasabi.
The wasabi is made from the grated rhizome of the wasabi plant also known as the Wasabia Japonica.
The Wasabi paste that is sold in many restaurants and in U.S. grocery stores is imitation wasabi and not real wasabi.
Imitation wasabi is made of horseradish, green food dye and mustard powder.
Imitation wasabi mimics the flavor and the color of real wasabi and is commonly used in Western restaurants.
Real wasabi is a root vegetable in the mustard family of Brassicaceae.
Real wasabi also has a potent flavor and aroma and is finely grated into a paste and uses an oroshigane and is also difficult to grow because real wasabi requires specific growing conditions.
Real wasabi is also expensive and loses it's intensity within 15 to 20 minutes of it being grated.
The real wasabi is also made of Japanese Horseradish and is the plant known as the Eutrema Japonicum or Wasabia Japonica.
Fake wasabi is instead made of European horseradish and often with green food coloring added to it.