Sea salt is produced by evaporating seawater, meaning it retains trace minerals from the ocean like iodine but I don't use it anymore because of the Japanese putting fukushima back into the sea and other chemicals that can't be removed like PCBs (polychlorinated biphenyls), PBDEs (polybrominated diphenyl ethers), pesticides, and certain industrial chemicals
while table salt is mined from salt deposits and heavily processed to remove most minerals kosher is definitely the way to go with salt. There however are exception such as Himalayan salt, the Danakil Depression salt (salt alley) or Utah's Real salt are all minimally processed and Kosher salt is not as processed and often contain no additives like regular salt.