What is the difference in canning salt and regular table salt? Can they be use interchangeably?
I believe you can use them interchangeably. Canning salt doesn't have the anti-clumping additives of table salt. Those additives can discolor some canned foods. Because it it is without those additives, it is more likely to clump than table salt.
No, they shouldn't be used interchangeably, if they could, recipes would not specify canning salt. Table salt will turn the contents dark, the brine cloudy, and settle to the bottom of the jar - all caused by the iodine and anti-caking additives. Kosher salt, however, can be used.