system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the heat you feel from eating horseradish different than the heat you feel from eating hot sauce?
gpt
Hot peppers contain capsaicin, a chemical which "tricks" heat sensitive nerve endings in your mouth and causes those nerves to send a fake "this is hot" signal. More capsaicin equals more spicy.

Horseradish and wasabi (although to be honest you may have never eaten real wasabi, commercially available wasabi paste is usually just horseradish with green food colouring) anyway horseradish has a completely different spicy chemical, alllyl isothiocyanate, which is also responsible for spiciness in mustard. You feel this more in your sinus as the vapors are released when you consume horseradish and they rise up inside the back of your pharynx where it interacts with TRPA1 nerve endings and sends a "pain" signal

Garlic has yet another spicy chemical, allicin.

Black pepper has piperine.