Pepper spray and pepper gel are two types of self-defense sprays that are designed to incapacitate attackers by causing a burning sensation in the eyes and throat. The main difference between the two is the consistency of the active ingredient, capsaicin. Pepper spray is a liquid that is sprayed in a stream pattern from a canister using a stream or mist, while pepper gel is a thicker, gel-like substance that is fired from a canister using a or foam-like stream.