Big-food (the industrial food producers) attempts to compare the difference between organic and non-organic food by asking the wrong questions (on purpose) - whether organics taste any different from non-organics, and whether there is a difference in the nutritional content. Tastewise there may or may not be much of a difference. Regarding the nutritional content, if you simply count the calories and other building blocks you may not find that much of a difference either. The most important difference between organics/biodynamics (a sort of Über organics - see a previous post on that) and non-organics has to do with soil and micronutrients.
For one, non-organic produce has pesticide residue on the outside. But perhaps more importantly, non-organic produce grows in depleted soil that must be enhanced with chemical fertilizer. And to top if off (pun intended), it gets treated topically with fungicides, pesticides and herbicides, all of which seep into the soil. The produce then absorbs this chemical cocktail through the roots, which becomes part and parcel of the produce you eat, an issue the two questions diplomatically leave aside.
Soil that gets enhanced naturally with manure and compost is inherently much richer in minerals and trace elements and devoid of chemical toxins. You know if you have such soil in your home garden if it is dark and crumbly and full of happy little creepy crawlies. It should look like Mississippi Mud Pie. Produce that grows in such Mississippi Mud Pie soil is in turn much richer in minerals and trace elements. It is this richness that makes such food packed with real nutritional value. Not only is it much more nourishing, we also need to eat less of it (!) to feel satisfied. No empty calories here.
So even though our soil has been depleting steadily with the advent and the spreading of industrial agriculture over the past hundred or so years, it is still better for our health to opt for organically, or better yet, biodynamically grown produce and grains.