What's the difference between lactose intolerance and milk allergy?

Big difference: In lactose intolerance the small intestine can't digest lactose into glucose & galactose. These 2 sugars but not lactose can be absorbed. If lactose reaches the large intestine bacteria break it down to lactic & co2. Lactic acid causes diarrhea. Co2 is a gas causing bloating, cramps &...Well, gas. Allergy involves the immune system with symptoms like hives, eczema, asthma, vomiting & anaphylaxis.

See below : Lactose intolerance is an actual problem with metabolizing the sugar lactose. This can be due to the genetic lack of the enzyme, inefficient enzyme or virally induced destruction of the villi in the gut where the enzyme is produced resulting in lack of the enzyme temporarily. Milk allergy is a response where the body has created an immune response to milk proteins and they can't be tolerated.

Milk issues: Milk allergy causes hives, swelling of soft tissues such as lips and tongue, shortness of breath and in extreme cases anaphylactic reactions, it may also cause severe abdominal cramps. The effects are immediate after milk ingestion. While lactose intolerance can cause gas and bloating 1-2 hours after ingestion of dairy products and sometimes diarrhea.