Synthetic fertilizers feed the plant and usually only contain macro elements, such as nitrogen, potassium, and phosphate. Organic fertilizer is a more balanced fertilizer, including the same macro elements, but also micro and trace elements that are not usually found in chemical fertilizers. It also has other attributes, like amino acids, fulvic acid, and organic carbon that would feed your soil, as well as stimulate microbial life in your soil to feed your plants.