This is a question I have asked myself a number of times and I finally have taken the time to find the answer. My understanding is that organic refers to how food is grown whereas natural refers to how food is made/produced or processed. Of course this is an over simplified definition so I'll break it down further.
Organic and organic certification as defined by the National Organic Program (NOP) is:
"Organic certification is a certification process for producers of organic foods and other organic agricultural products. In general, any business directly involved in food production can be certified, including seed suppliers, farmers, food processors, retailers and restaurants. Requirements vary from country to country, and generally involve a set of production standards for growing, storage, processing, packaging and shipping that include:
* avoidance of most synthetic chemical inputs (e.g. fertilizer, pesticides, antibiotics, food additives, etc), genetically modified organisms, irradiation, and the use of sewage sludge;
* use of farmland that has been free from chemicals for a number of years (often, three or more);
* keeping detailed written production and sales records (audit trail);
* maintaining strict physical separation of organic products from non-certified products;
* undergoing periodic on-site inspections.
In some countries, certification is overseen by the government, and commercial use of the term organic is legally restricted. Certified organic producers are also subject to the same agricultural, food safety and other government regulations that apply to non-certified producers.
The NOP covers fresh and processed agricultural food products, including crops and livestock. It does not cover non-food products that may be sold as organic, including natural fibers (eg: organic cotton), and health and beauty products (eg: organic shampoo).
So, it is certainly a good idea to buy organic whenever possible. Not only are you putting something safe into your body, you are supporting a more sustainable approach to farming.
Natural foods are foods that do not contain artificial ingredients and are minimally processed. They do not consist of ingredients such as refined sugars, refined flours, milled grains, hydrogenated oils, artificial sweeteners, artificial food colors, or artificial flavorings. You may find that some products will fall into both classifications which is all the better. But worst case, if you can't buy organic, try to buy natural.