The lay of a wire rope describes the manner in which either the wires in a strand, or the strands in the rope, are laid in a helix.

Regular lay wire rope: the direction of the individual wires is opposite to the direction of the strands.
Lang's lay wire rope: the individual wires have the same lay direction as the strands.

Left-hand ordinary lay (LHOL) wire rope (close-up): Right-hand lay strands are laid into a left-hand lay rope.

Right-hand Lang's lay (RHLL) wire rope (close-up): Right-hand lay strands are laid into a right-hand lay rope.

Regular lay wire rope is less likely to untwist, easier to handle and less subject to crushing while lang's lay wire rope provides improved bending fatigue and greater wear resistance, accepted for a wide range of applications.

Lang's lay rope will untwist if one end is free to rotate, limited to applications where both ends are permanently fixed, such as drag lines.
Rotation resistant ropes are a special category (class) of wire rope designed to resist the tendency to spin or rotate under load.

19x7 (18x7 WSC) Rotation Resistant:-

19 strands containing 7 wires each. The 7x7 core is in left lang lay, coupled with 12 outer strands of right regular lay.

8x19 IWRC Rotation Resistant:-

8 strands containing 15 through 26 wires each. The 7x7 core is in left lang lay, coupled with 8 outer strands of right regular lay.