Throughout the Nutra Foundation website, a variety of terms are used which are in most cases interchangeable.
Natural Products is a catch-all for any product (or food/mineral/etc.) which is produced inherently in nature and has defined medicinal properties and positive effects on overall heath. Some people might also include Organic products in this category, though this term tends to refer primarily to foods.
Nutraceuticals is a relatively new term coined by the natural products industry to connote the fact that in many cases these products can be viewed on a parallel level with pharmaceuticals.
For example, a highly renowned MD and neurosurgeon that I am acquainted with in Pittsburgh, PA treats a considerable percentage of his patients using Fish Oils (Omegas) to reduce pain and inflammation — in addition to, or instead of, using pharmaceutical products.
Supplements generally refer to those products sold in natural product and drug stores for a variety of uses. Vitamins are a sub-category of supplements.
Whatever the term used, they all have the same thing in common — these are products and elements derived from natural sources to treat and alleviate a plethora of ailments and illnesses.