What's the difference?

Organic is primarily a labeling term that is used on a wide variety of foods that have been produced through methods and practices approved by the U.S. Department of Agriculture (USDA) and its National Organics Program (NOP). Organic is also one of the single best steps you can take to safeguard the quality of your food. In many cases, organic is also good step for the environment.
Many people think about "organic" as meaning "earth friendly." Even though this meaning often holds true, it doesn't always. Organic regulations focus on farming practices and food production steps that can be monitored and controlled to decrease risk of food contamination and improve food quality. But for the most part, organic regulations simply do not try to address more complicated issues involving the earth and sustainability.
Here is one simple example of the difference between the focus of organic regulations and a focus on sustainability. In the U.S., we currently plant about 92 million acres of corn, 78 million acres of soybeans, and 57 million acres of wheat. Ecologists view these 227 million acres and the way they are planted as non-sustainable. Many factors combine to make our current planting of corn and soybeans and wheat non-sustainable. Included are factors like natural water cycles and natural mineral cycles in North America and their inability to accommodate the 227 million acres of these three crops as currently cultivated. The USDA's organics program does not address or evaluate the sustainability of these crop acres. The program limits its focus to the farming steps that would be needed in order for all 227 million acres of corn and soybeans and wheat to be certified as organic. For example, USDA organic guidelines would prohibit use of genetic engineering, fertilization with sewage sludge, and irradiation on any of these acres. Such changes would most likely improve the quality of the crops and the quality of the land. But the practice of planting 227 million acres with these three crops would still be non-sustainable, and this non-sustainability would not matter from the USDA's perspective. Provided that USDA organic requirements were met, these crops would be labeled organic regardless of their sustainability. The bottom line here is simple: organic food production is better for the environment and better for our health than conventional food production methods, but important earth-related questions like sustainability are not typically addressed in organic regulations and might not be furthered by adoption of organic standards.
Of special importance in organics are the "big three." Genetic engineering, irradiation, and sewage sludge are sometimes referred to as "the big three" by commentators on the National Organics Program, since they are practices that can have an especially problematic impact on health and the environment. The "big three" have always been - and are still - prohibited by organic regulations. Along with prohibition of these three practices, however, a wide variety of other practices are prohibited in production of organic food. For example, most synthetic chemicals (including most synthetic pesticides, herbicides, and fertilizers) are prohibited by organic regulations. All off these prohibitions in organic food production are important. They help to safeguard the quality of our food and to reduce our health risk from food contaminants.

George Mateljan Foundation