[Rudy]

Olddigger, the difference is simply because they are different.

Indian head coins struck between 1859 and 1864 contained 88% copper and 12% nickel, as required by law.

In 1864, the alloy changed to 95% copper and 5% tin and zinc, and the weight of the coins was reduced from 72 grains to 48 grains.

Why the change in composition? Mint research in 1863 had indicated that bronze was an excellent alloy for minor coins, and so the copper-nickel alloy was discontinued. Another possible contributing factor for the change was the whitish color of the early cents, which combined with their size was enough to confuse many merchants into thinking they were dimes.