The difference between Din, and Halacha-

The main difference between Halacha, and Din is, Din is the original judgment. I.E.- Everyone agrees, that you must put Tsitsit on a four cornered garment, but there is a discrepancy in how many strings. The din there is that one must have Tsitsit on a four cornered garmet, but the Halacha is that there must be four strings.