How exactly does antimatter differ from matter?

with antimatter, the charges of the molecules are reversed. Protons are negatively charged while electrons are positively charged... Antimatter sort of follows Newton's 3rd law of motion, "to every action there is an equal and opposite reaction." which basically says that to anything that you consider matter (aka, computer, chair, even air is matter) there is also antimatter in the same amount. Some believe that when the big bang happened, matter exploded off one way and the antimatter went the opposite direction. Seeing that there is no way of proving that, other than getting a spaceship that does warp 20 speed (impossible), we are forced to simply believe that's how it is.