Specialist vs. cross-industry credential
The CISSP is a security specialist credential. It signals deep expertise within one specific professional domain — information security — and is recognized within that field.
The PMP is a cross-industry credential. It signals project management capability that applies to virtually any field — construction, IT, healthcare, manufacturing, government, security. PMI's brand is industry-agnostic, and the PMP is one of the most widely recognized professional credentials globally regardless of vertical.