There are many types of batteries depending upon the usage. For instance there are primary and secondary batteries, wet and non-wet (gel-type) types, conventional and maintenance free, and even wet-charged and dry-charged batteries a secondary battery can either be wet or gel-type, conventional and maintenance free.
A dry-charged battery is stored on the dealer's shelf without electrolyte in it. The dealer must put electrolyte in the battery and briefly charge it before installation in the vehicle.
Maintenance free batteries are constructed differently than conventional batteries. They have lead-calcium plates instead of lead-antimony plates. This reduces the amount of electrolyte loss because there is less gas production. These batteries are wet-charged and have a longer shelf life due to a low discharge rate.
Dry-charged batteries have the advantage of a longer shelf life. Wet-charged batteries are usually ready to go from the dealer's shelf with little or no charging.