Surfing wetsuits are a breed unto themselves. To begin with, there are cool, surfer-dude designations used to describe the different styles of surfing wet suits.
The first is the spring suit which has short legs and short arms and is used to keep the upper body warm and has a thickness of materials of about 2mm. Short Johns are like spring suits but without the sleeves and are also usually 2mm thick. Long Johns have full-length legs and are mostly about 2mm thick. Full Suits are self-explanatory, the most commonly used -- especially in colder waters -- whose thickness is determined by the temperature of the water the surfer usually finds himself in.
Another difference in surfing wet suits is that many have two layers of material and the area under the arms is thinner than the rest allowing for easier arm movements critical to performing well while surfing. Furthermore, it is common for surfers to add an additional spandex suit underneath their wetsuits if they venture into cooler waters.
Surfing wet suits need to be more flexible in the upper torso and shoulder areas than diving wet suits to make the balancing and control contortions of the surfer easier. Especially sensitive are the knee areas as the surfer is constantly shifting his weight to maintain his balance.
Unless the knee areas move easily and don't stretch during this movement they will inhibit the surfer and cause the suit to crack with wear at the knees over time. Because of the extreme physicality involved with the sport of surfing, the entire suit has to be manufactured with ease of movement and durability at its core.
Unlike other wetsuits, surfing wet suits don't really care about thermal heat loss as much as diving suits. And because of the movement capability in the suit, gender specific manufacture is mandatory.