Friction drag is the drag force EXERTED by a fluid on the SURFACE DUE to friction action when the FLOW occurs past a flat surface at ZERO incidence. Pressure drag is the additional drag force on account of the differences of pressure over the body surface when flow occurs past a surface which is not everywhere parallel to the fluid stream. Pressure drag depends upon separation of boundary layer and the size of wake. Friction drag is due to shear stresses generated due to viscous action.

Friction drag is the drag force exerted by a fluid on the surface due to friction action when the flow occurs past a flat surface at zero incidence. Pressure drag is the additional drag force on account of the differences of pressure over the body surface when flow occurs past a surface which is not everywhere parallel to the fluid stream. Pressure drag depends upon separation of boundary layer and the size of wake. Friction drag is due to shear stresses generated due to viscous action.