Question

how common salt and iodised salts are different from each other in terms of purity in science​

Answer 1

Both types of salt taste the same, look the same, and feel the same. However, the iodized salt has potassium iodate in it, along with some dextrose and anti-caking agents. These additive are necessary because otherwise the potassium iodide may evaporate or cause clumping.