"Sea salt" in recipes is off the same shelf as the one that says "free range eggs", a shorthand way of saying "I know what I need to say to be right on"
There are differences in flavour and intensity, which come down to texture and odd minerals and bird poo. it's one thing to sprinkle a couple of grains on an egg or a slice of toast and (unsalted) butter but I would defy anyone to tell the difference once it has been used to season.
There's also the question of useability, coarser lumps are easier to control the quantity but (slightly) harder to amalgamate. I keep a salt pig of sel de guerande (that's bird poo salt one upmanship if ever there was) for ease of use, but when I can, eg for bread baking, I dissolve and pour off leaving the sediment behind. (What? and miss out on all the good stuff ??!? )