What this coin looks like (obverse, reverse, mint mark location, special features, etc.):
There were two major varieties of the 1838 Seated Liberty silver dime. The difference is related to the size of the stars along the rim of the obverse of the dime. One variety had small stars while the other had larger stars. The small stars are slightly smaller and "spiky" while the large ones are "fatter" as depicted in the example image above.
Another unrelated variety is the 1838 "Partial Drapery" dime. This coin features what looks like drapery added between the arm and leg on the sitting liberty. This is actually an accidental die clash error and was not part of the official design of the coin. This "partial drapery" is depicted by the arrow in the example image below: