In both Engineering, Procurement, and Construction (EPC) and design-build projects, the contractor handles design and construction, but they have some key differences.
With EPC agreements, the contractor delivers a finished product in a turnkey fashion. That means the designs are generally simpler, but the final result is a building ready to open. With an EDP, the designs are usually complete before construction begins.
Design-build contractors usually provide more ongoing design work, and projects can often begin construction before the design is complete. However, that may mean the building requires additional changes throughout construction.