Are both 1988's? If not that might be the difference. Although most designs remained about the same. Each year has a small change in the die. Correction; Some dies have been used for years,But some small changes have been made when a die wore out.
That’s what I like about coin talk the most you learn every time u post but I did good by catching the coin and I Learned about the die change, thank you for your time and for posting in a learning ,,, way god blessed ya.
According to the Secretary of the Treasury the nickel can't have a weight variance more or less than .194 gram. So that's a pretty heavy nickel.