What's the difference between organic and biodynamic?
While "organic" usually means free of synthetic pesticides/herbicides/hormones/antibiotics/pollution/etc., "biodynamic" takes it a step further and means a farm system based on healthy mineral-rich soil with good microbes. So while "organic" focuses on being "toxin-free", "biodynamic" focuses on being "nutrient-rich".
Of course the two terms are not mutually exclusive. By definition biodynamic is also organic (soil needs to be clean to be healthy), but organic doesn't necessarily mean biodynamic (it can be free of toxins, but still depleted of nutrients).
I try to get biodynamic when I can. Still, organic is better than industrial (which is nutrient-poor and contaminated with toxins), and of course any fresh food even from industrial farming is still better than instant/junk food.
The concept is more important than the terminology, though the terms do help. The International Assessment of Agricultural Knowledge, Science and Technology for Development (IAASTD)-- a global involving FAO, WHO, World Bank, UN, and over 100 countries-- discussed "agroecology" which describes farming approaches that mimic natural ecosystems in order to produce food that is clean and nutritious, while minimizing pollution and maximizing soil fertility. Other related terms are "permaculture", "grass farming", and "soil farming".
Here's an excerpt from http://www.globalagriculture.org/report-topics/agroecology/agroecology.html --
Agroecological systems, such as organic farming, permaculture and other variants, are knowledge-intensive, tend to use less or no externally-supplied synthetic inputs, and seek to generate healthy soils and crops through sustainable management of agro-ecological cycles.
They make better use of local resources in small-scale agriculture which can improve productivity and generate worthwhile innovations. Agro-ecological and organic farming can achieve high production efficiencies on a per area basis and high energy use efficiencies, outperforming conventional industrial farming in both areas. Despite having lower labour efficiencies than (highly-mechanised) industrial farming and experiencing variable economic efficiency, latest calculations indicate a capability of producing enough food on a per capita basis to feed the current world population. Their higher labour demand compared to conventional farming can be considered an advantage where few alternative employment opportunities exist.