Paprika will uplift your dishes with subtle earthy notes and a gorgeous red colour, without ever overpowering the other ingredients. Making the spice a true team player.
When substituting, use common sense. Cayenne pepper is as much as 50 times hotter than sweet paprika, so a 1:1 substitution wouldn't work unless you want some heat—the right substitution, in this case, would be 1/3 of a teaspoon of cayenne per 1 teaspoon of paprika. Make an informed decision, but also use thorough recipes that might suggest reasonable substitutions.
In summary, chili peppers are the fruits of plants from the Capsicum genus that contain capsaicin, the compound responsible for their heat.