Regular fleece is the weight that people use for making blankets and mitten and scarves and things like that. It's much thicker than microfleece. In diapering, you would use that type of fleece for a diaper cover. I believe some people use it for the outer layer of an AIO diaper, as well.
Microfleece is much thinner and softer than regular fleece - it will drape better, and the print will look less "fuzzy". This is the sort of fleece that people use to make lounge pants - it's about the thickness of sweatshirt fabric. This is the sort of fleece that you'd want on the inside of a diaper, touching the baby's skin - it will let wetness pass through easily, but it won't keep the baby's skin wet.
Does that help any?