For the light magnesium oxide, it has already introduced that light magnesium oxide is white powder, odorless, tasteless and nontoxic. The chemical name is MgO. And the heavy magnesium oxide is directly burned by magnesite. As a matter of fact, it is produced by heating magnesium carbonate.
Preparing light magnesium oxide is complicated. For the differences between the two, Meishen Technology gives you some references:
Firstly, the manufacturing technique. The light magnesium oxide: in general, making the magnesium chloride, magnesium sulfate or magnesium bicarbonate to become the product which is water-soluble. And then, making then water-fast products through chemical method. Finally, calcining it into magnesium oxide. The bulk density is small in general.
Secondly, the heavy magnesium oxide is directly burned by magnesite and brucite. The bulk density is small.
Thirdly, we can see the difference between the light and heavy magnesium oxide from a macroscopic view. The light magnesium oxide has a larger volume, and most of them used in mid-to-high end industries. The heavy magnesium oxide has a smaller volume, and most of them used in low-end magnesium oxide.