Commercial versus military warship standards

What is the difference between a commercial-grade warship and a military-grade warship?

It is a spectrum: some ships use commercial standards throughout, while others adopt only selected commercial practices and retain military requirements elsewhere.

Commercial-grade construction is a spectrum rather than one fixed category. A warship may use commercial assumptions for compartmentation, steel, and fire prevention across much of the design. Another vessel may adopt only limited commercial practices to reduce cost while keeping the rest close to naval standards. The practical question is which standards changed and what survivability or damage-control consequences follow.