The main difference is in installation; batt insulation comes in pre-cut pieces, while roll insulation is installed by rolling it out between ceiling joists.
Calculate the amount of insulation by dividing your attic's square footage by the coverage area of the insulation package you plan to purchase.
Unfaced insulation is ideal for new construction, remodels, and interior walls, floors, ceilings, basements, attics, and crawlspaces that do not require moisture control.