From a surf kayak now land locked:
there is a big difference, the basic skills such as rail control etc.. but the dynamics are so different. in a river the water is moving while an ocean wave the wave is moving. It is very hard to put into words the exact difference and keep it under 500 words. But the big thing is just the fact you are moving in a forward motion vs standing still as a river wave does move. But just go and have fun. Hint on the paddle out: if it is big dont stop paddling untill you make it to the outside..