Yeah. I imagine it's just that the Kosher salt has been declared Kosher by a Rabbi, whereas the bog standard salt hasn't been so although it probably would be Kosher, no-one's declared that it is. For some reason it's usually non-iodised; I can't think of any obvious reason why adding iodide would make it non-Kosher, but then I'm not even Jewish, let alone a rabbinic scholar. However, the fact that it is non-iodised has caused people who believe the salt iodine fish myth to suggest it be used instead of standard table salt, which in the US does often contain iodine.