Attic insulation, especially fiberglass, should be replaced every 15-20 years, particularly if it has been exposed to moisture or mold.
Double bubble insulation consists of two layers of polyethylene bubbles between two metalized coatings, effectively preventing frost and condensation in various structures.
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.