Pickling salts and kosher salts differ in shape and coarseness. Pickling salt has finer and more regular shaped granules while kosher salt granules are larger and coarser. Because of these differences, both are used in different ways and recipes. However, one thing they do have in common is that they both do not contain iodine
Pickling salt, as its name connotes is best used for making pickles. Pickling salt does not contain additives that would otherwise cause discoloration in pickling.
Its smaller and more compact granules allow for more accurate measurements. This is because there is less air inside each granule meaning you are able to get more actual salt in a single measurement than if you were to use kosher salt.
Kosher salt has a larger surface area and easily adheres to other ingredients. It best used for brines, for salt crusts on meats or as regular table salt. Kosher salt is also great for garnishing dishes and drinks because of its large granules.
Both types of salt can be used interchangeably as a simple condiment, however, do note that some kosher salt brands contain anti-caking additives that might throw your recipe off. Additionally, if you are using kosher salt for pickling, you should add at least 50% more to get the same taste as if you were using pickling salt. It is not advised to use either form of salt in baking.