...Bitter is one of the five main tastes. It has a sharp and pungent profile. Bitter is a naturally occurring flavor in many foods, including coffee, chocolate, bitter melon, and chicory. Bitter is used sparingly to accentuate the flavors around it and can be mellowed by other tastes in both savory and sweet dishes.
...Spicy is a flavor that brings heat and fire to food by creating a burning sensation in the mouth or sinuses. Spicy flavors come from hot peppers, horseradish, and wasabi. Spicy adds a kick and sometimes complexity to a dish and releases endorphins, creating a mildly addictive quality.