Net slip is the distance between two originally contiguous points, offset by a fault. Net slip has two components, a dip-slip component and a strike-slip component as shown in Figure 1. Net slip and separation are the same if the line along which separation is measured parallels the net slip.

Figure 1. Illustration showing net slip, its strike-slip component as well as dip-slip component. By K.P. Hefferan, available from http://www.uwsp.edu/geo/faculty/hefferan/geol320/faults.html.