I'm not sure, just overall I have both albums at 320kps and when I play either they just sound much more raw and more structured on Heat. Not to mention the drumming was great for their genre on that album which was a main reason why I liked them. Not a fan of all the weird sound effects added on III, but I guess that's every band now.
Love Crummet to death, but he has changed his style a bit. Heat was very crunchy and ferocious sounding but a lot of his more recent work is more "rounded out" sounding. Works great for non heavy bands, maybe not so much heavy bands.