Salt. We have more choices than ever it seems.
So what is the difference?
Are some salts really saltier than others?
The short answer is no.
The real answer is that bigger flakes have less salt per volume. The salt chart available in The Science of Good Cooking should help explain. The results were determined by weighing out each brand of salt per volume and scaling them so they all contain the same amount of salt by weight:
Brand Amount Equal to 1 Tsp Table Salt
Maldon Sea Salt 2 teaspoons
Diamond Crystal Kosher Salt 2 teaspoons
Espirit du Sel Fleur de Sel 1 1/3 teaspoons
Light Grey Celtic Sea Salt 1 1/4 teaspoons
Morton Course Kosher Salt 1 1/4 teaspoons
Fleur de Sel de Camargue 1 1/4 teaspoons
Morton Salt (noniodized) 1 teaspoon
Morton Iodized Salt 1 teaspoon
La Baleine Sea Salt 1 teaspoon
So as you can see, Diamond Crystal Kosher Salt is just less tightly packed than more regularly shaped salts. Just because you use twice as many teaspoons/tablespoons of Diamond as you would normal table salt, doesn’t mean you’ve actually added any more salt to the dish.