Re-insulation can use all of the same materials for insulating a new home, but some are much easier to use for re-insulation than others; it’s not usually efficient or reasonable to tear down all of your walls to install new fiberglass batts, for example.
For this reason, re-insulation largely utilizes blown-in and spray foam insulation, which can be applied in difficult-to-access areas and/or directly over existing insulation with a minimum of difficulty.