Sea salt is made by evaporating sea water. Sea salt contains many trace elements and other things that are good for you. It will be coarser grained than regular table salt, and many say it has a better flavor. The impurities we mentioned earlier that are removed from regular salt are the plus ingredients found in sea salt. Kosher salt is a coarse-grained salt that has no added ingredients.
Coarse salt is exactly that, coarse-grained regular salt.
In this family is found rock salt, which is used to melt ice off roads and to drop the temperature in the ice-cream freezer. It's also used in cooking to make salt-crusted roast and as a bed for oysters Rockefeller. Dairy salt comes in this category, too. I was raised on a dairy, but we never did use any dairy salt. I don't know what its special use is, could be used in making cheese and salty butter.