Good question! Can you use a windsurfing wetsuit for surfing and vice versa? Sure, but there are quite a few differences between windsurfing and surfing wetsuits. They came from the fact that while surfing you are sitting in the water most of the time and during windsurfing your are above the water most of the time so conditions are a bit different. Then there is also the shape of the wetsuit that must follow the usual body position and it must allow the range of motion specific for each sport.

Windsurfing wetsuits

These are some windsurfing wetsuits specific features:

• Lots of smoothskin neoprene (single lined neoprene); smooth neoprene on the outside of the wetsuit reduces windchill since it repels water and it does not get wet. In surfing wetsuits neoprene is mostly double lined meaning it is also lined with nylon on the outside. Nylon gets wet and when you have wet nylon + wind you have more windchill. Of course windsurfers have lots of wind so...
• Windsurf-specific arm cut; windsurfing wetsuits also have a specific arm cut to prevent cramping during sailing as you grip the boom.
• Durable neoprene; neoprene in windsurfing wetsuits is usually more durable (and a bit stiffer).
• Velcro ankle closures; these help you drain water from your legs and the tighten them so they don't slip up.

Surfing wetsuits