What's the difference between 81/85 PU and 60/81 PU?

Alright so I'm a guitarist looking to buy a new guitar and the ESP FX series kinda caught my attention, just I play heavy stuff and ALL my guitars have 81/85 EMG Humbuckers and I have no idea what the 60/81s will do to me. So could someone please explain what the differences will be. My main guitar is an ESP LTD MP-600 if you wanna compare it to another guitar.