SIP an IP are paint correction products which contain abrasives. They are used to prepare/perfect the finish prior to waxing or sealing. They are designed to remove paint imperfections, not cover them. It's all in the Prep.
Z2 and Z5 are sealants. They protect the paint and increase gloss (Z5 has minor filling capability). However, their results are limited by the paint's condition. Neither one will remove scratches. They can marginally improve a poor finish, but polishing/correcting with products like SIP/IP make all the difference.