An overlay or resurface project involves the application of approximately 2 inches of asphalt concrete to the existing surface or pavement of the road to help prolong the life of the road.

Resurfaced road

Overlay or resurface treated roads might undergo repairs to fix cracks and potholes.  These repairs are performed before the overlay or resurface and won't be visible after.

Road workers resurfacing a section of road.

Related:
Road Treatment: Seal
Road Treatment: Reconstruction