Weight and Purity
According to the U.S. Mint, silver coins were originally produced to be used as money rather than as an investment. The amount and purity of silver in coins varies from year to year and is typically less than in rounds of the same size. Silver rounds typically contain 1 oz. of .999 pure silver.
Numismatic Value
U.S. silver coins have not been produced since 1964. They are valued for their numismatic, or collectible, value as well as their silver content. Refiners and governments still produce rounds. According to the American Numismatic Association, they have little or no collectible value.
Resale Value
Silver rounds issued by small refiners often sell for less than rounds issued by large refiners or coins and rounds issued by governments. They are not widely recognized, so many buyers will avoid purchasing them. Sellers of coins seldom have trouble finding buyers for their silver.