Step 1: Picture how the wires actually sit on the rope's surface.
In an ordinary lay rope, the individual wires within a strand twist in the opposite sense to the way the strands twist around the rope, so each outer wire only shows a short segment on the surface before diving back inward, roughly parallel to the rope's length. In a Lang's lay rope, the wires twist in the same sense as the strands, so each outer wire lies at a shallow diagonal angle and exposes a much longer stretch of itself along the rope's surface.
Step 2: Connect that geometry to wear resistance.
Wear happens where a rope repeatedly rubs against a sheave or drum. Because Lang's lay wires present a longer contact length to the sheave for the same length of rope, the wear from that rubbing gets spread thinly over a bigger wire surface instead of being concentrated on a short exposed segment, so the rope lasts noticeably longer under abrasive service.
Step 3: Connect it to bending fatigue as well.
When a rope repeatedly bends around a drum or sheave, its individual wires must flex and slide slightly against each other. The diagonal, longer running wires of a Lang's lay rope can accommodate this bending with more give and smoother internal movement, which reduces the stress concentration that leads to fatigue cracking, giving it superior resistance to bending fatigue compared to an ordinary lay rope. Left and right hand lay only describe the twist direction and apply equally to either construction, so they are not the deciding factor here.
\[ \boxed{\text{Lang's Lay}} \]