Manure is obtained naturally by the decomposition of dead plants and animals. Fertilizers are chemical substances and are not typically natural. It is not very rich in nutrients. It is rich in soil nutrients like nitrogen, phosphorous, and potassium. Manures are relatively less rich in plant nutrients; they only remove the general deficiency of soil.
Organic fertilizers serve as a supplement to the traditionally used chemical fertilizers. These are carbon-based compounds obtained by converting organic substances into a usable fertilizer by modified aerobic-cum-anaerobic composting. These fertilizers improve the soil fertility and water retention capabilities/capacities and replenish the nutrients in the soil.