What is the difference between food allergy and food intolerance?

None. Same same.

An allergy is a response by your immune system that releases histamine. Histamine causes inflammation and muscle constriction, and a variety of other responses. Food allergies can cause reactions such as itching, hives, tingling and swelling of the mouth and tongue, reactive asthma, and anaphyllaxis.

A food intolerance is any reaction to food that is not a histamine response. For instance, lactose intolerance is the inability to digest milk sugar. It's not an allergy, but it can cause great discomfort, such as gas, bloating, and diarrhea. Gluten intolerance is another food intolerance ( the protein in most grains) that is not an allergic response.

Intolerances can be equally as severe and life-affecting as allergies. For that reason, many people with intolerances skip the complicated explanation and just say, "I'm allergic to [whatever]."