What is the difference between sprung and unsprung handles?

Sprung handles have a deeper rose (approx 8mm- 10mm) to accommodate the internal spring mechanism. This mechanism returns the lever back to its natural horizontal position

Unsprung handles have a less deeper rose (5mm) as they have no internal spring mechanism which is a look preferred by architects.

Unsprung handles need to be used with sprung Architectural quality locks.