What is the difference between monocoque and body-on-frame construction?

Monocoque (unibody) construction integrates the body and frame into a single welded structure, offering lighter weight, better crash energy absorption, and improved fuel efficiency - common in passenger cars. Body-on-frame uses a separate ladder frame onto which the body is mounted, providing higher load-carrying capacity and easier repair, making it preferred for trucks and SUVs like the Toyota Fortuner or Mahindra Thar.