Q.  Is there a difference between the terms “wheat-free” and “gluten-free” on a food label?

A.  Yes.  While these terms often appear together on a food label, they have very different meanings. 
 Wheat-free means there are no wheat flour ingredients in a food (such as whole wheat or all-purpose flour).  This term is helpful to people who have allergies to wheat and wheat flour products.  Wheat is one of the most common food allergies.

Gluten is a component of many grains including wheat, barley, and rye.  So, gluten-free is a much more restrictive term.  A gluten-free food, means that there are no derivatives from these grains. 

A gluten-free diet is the only treatment for people who have celiac disease, one of the most common genetic disorders in the world.  It is an autoimmune disorder, in which the body cannot tolerate gluten, the protein component of grains.   Gluten is toxic to the small intestine and damages it, preventing nutrients from being absorbed into your body.  (Gluten literally destroys the villi, which are like little straws in your digestive tract, which enable you to absorb nutrients from what your eat or drink).
 
For the celiac patient, even tiny amounts of gluten are harmful, including surprising food ingredients such as: soy sauce, malt extract (a flavoring used in many cereals and packaged foods) and beer.  But
 Someone with just a wheat allergy could eat a gluten-free product whereas, someone with celiac disease could not assume that a wheat-free food is gluten-free, because it could contain barley, rye , oat and/or their derivatives.  (Note, while oats are technically gluten-free, in the USA, they are usually cross-contaminated with wheat, so they are usually excluded)