Looks like you are comparing 2 totally different coins with 2 different normal planchet diameters.. do you see the stars above the head? 2 different styles. Braided Hair Cent 1851 - 27.5 mm (minted from 1839-1857) Classic Hair Head Cent 1810 - 29 mm (minted from 1808-1814)
Thank you guys for you're insight but as you can see I've already received a very intelligent and detailed answer