You can place all your equips in the sump which you don't want to see in your main display tank. Protein skimmers, heaters..etc. Also the additional volume of water from the sump would contribute to water parameters stability. A compartment for refuge can be set up to grow pods and algae which again helps in water parameters. Additional live rocks in the sump also helps in ammonia detoxifying.
No sporotofthesoul what i ask is if you have live rock in the aqaarium well any other bio media be require and if not wont a refugium setup be better than a sump setup
A lot of people use the terms sump and refugium interchaneably. A sump is just an extra amount of water, along with space to hide heaters, skimmers, etc. A refugium has a section that allows the use of more live rock, macro algaes - essentially a small aquarium. I've heard of people keeping critters down in their fuge, ones that were not compatible in their main show tank!