As anyone who designs and builds surfboards, Ted Carrol, the protagonist of my novels 'Shaper' and 'Waves,' has his own ideas and pet theories about how boards work. He is quite willing to share those theories with any and all. It does not matter whether they are at all accurate as far as the books go; indeed, being a bit of a crackpot is part of Ted's character.
The fact is just about anything works for surfing. One can ride a rectangular piece of plywood (not that I would recommend it). It's mostly a matter of learning the quirks of whatever one is on, and dealing with them.
Most design differences are about control. Surfers may talk about 'speed' but, in truth, boards have always gone fast enough. That speed needs to be controlled somehow; otherwise we are hurtling straight toward the beach, unable to turn! Bottom shapes, outline, fins--all these things play a role, each element interacting with the others. And to some degree combining them is guesswork. The only true test of a shape is in riding it. Even there, the skill and preferences of the individual surfer make a big difference.
And, of course, what he or she is attempting to accomplish. Tricks in small waves? Survival in huge ones? Or just cruising along--each calls for its own equipment. Ted would be glad to shape whatever you need! :)