How do i find out how much different is the pill form of birth control from the shot you get every so often?

Extremely different: The pills contain 2 hormones, and are relatively 'lower' doses of those hormones, they are about 96% effective when taken properly, and usually regulate cycles, make periods lighter/less painful; the shots are 99% effective, have higher rates of irregular bleeding (and also - of stopping periods), higher risk of weight gain, and can cause prolonged suppression of hormonal functioning after stoppin.