SPRUNG WEIGHT :-- Sprung weight is a term used to describe the parts of a car that are supported by the front and rear suspension springs.
For e.g :-- Vehicle's frame , body , engine , driver , all liquids and the power train above the wheels.
These are quite heavy assemblies.
UNSPRUNG WEIGHT :-- The Unsprung weight includes wheels , tyres , brake assemblies , rear axle assembly and other structural members which are not supported by the suspension springs.
We can also say that all parts outboard from suspension springs.
The difference between two is also clear from the image.