Organic seeds must be produced according to organic standards and verified by a certifying agency. Standards prohibit synthetic chemicals, poisons and sewage sludge from being used in organic agriculture. Seeds may be hybrid or non-hybrid varieties.
Hybrid plants are developed by careful selection to enhance certain traits such as disease resistance, increased production and uniformity. Hybrid seeds are produced by crossing two specific parent plants; it requires hand pollination and isolation. Hybrid seeds will produce nearly identical plants, but the uniformity stops there -- seeds from those hybrid plants produce widely variable offspring.
Open-pollinated plants, commonly referred to as heirlooms, produce seeds that breed true (produce plants much like the parent plant). These varieties often have been grown for hundreds or thousands of years as seed is passed down from one generation to the next.