Most of the garlic available in grocery stores is softneck garlic; either Silverskin or Artichoke varieties. Silverskin has white, papery skin and stores very well. Artichoke garlic has fewer, larger cloves than the white variety and often is distinguished by some purple streaks. The artichoke variety is slightly more mild in flavour than the white option.
Hardneck garlic is more of a specialty item. This is where garlic scapes usually come from as well as very purple or large garlic such as elephant or porcelain garlic.