The regular repeating pattern which is the salt or sugar crystal shares much with the metal, in that individual crystallites grow from a seed, with the result that local areas have a long-range structure. However, as you will remember from your primary school days, sugar and salt crystals are grown from aqueous solution, and the remaining liquid has to be drained off. With liquid metal, the whole of the liquid matrix within which the crystals form will eventually solidify. For this reason, crystallites will be ‘frozen’ within a structure with essentially random orientation. The size of these ‘grains’ will depend on the rate of cooling and the number of nucleation sites.
There is a further difference, in that crystals grown from solutions
build up evenly on the outside, whereas those crystallising within
melts do so from the inside, and at varying rates, dictated by the
fact that solidification releases latent heat of fusion, with the
result that the growth of the crystal is tree-like (dendritic )
rather than linear.