There is a saying that a food allergy kills you and a food intolerance just makes you wish you were dead. Allergies and intolerances have different types of reactions, although some of the symptoms might be similar.
In general, a food allergy has a more severe immediate reaction and can lead to anaphylactic shock and death, in severe cases even trace amounts of an allergen can be fatal. Immediate swelling or itching of the mouth or extreme rashes on the body are clear food allergy symptoms.
A food intolerance can have a wide range of less severe, but non the less uncomfortable, symptoms. The symptoms can take minutes or even days to occur, which makes it difficult to identify the problematic foods. Also, a person could be having a food intolerance without knowing and just feeling less well. Most of the time it’s just difficult to bring the body’s reaction together with the causing food. Food intolerances can make you feel sick, energy less or cause rashes or even acne and can last for weeks. Depending on the severeness of the food intolerance you might be able to consume small amounts of the problematic food. At least may contains usually aren’t a problem, as these trace amounts, should be too little to cause a reaction.
So basically, an allergic reaction is quick and severe, whereas an intolerance reaction is slow and can last longer, you can feel pretty miserable, but it can’t kill you.