looking to buy d/w board for both downwind and flat water training,is there a differnce between dw paddles and surf sup paddles?

Yes, you can use the same paddle.

However, surfing specific paddles are typically cut a touch shorter than your Down Wind & Race Paddles.

Blade size is a bit of a personal preference. Some people like a smaller blade for Down Wind & Racing, which in theory delivers less fatigue to the engine (the paddler!), but others like a bigger blade, and slower stoke rate.... for cruising....

Down Wind & Race Boards are typically thicker, and bigger volumes, and you typically stand maybe 1 inch higher over the water, so an extra inch in the shaft can be handy. But not essential.

Which board are you interested in ??

I personally also have a preferrence for blade sizes between DW and flatwater paddling.

For Downwind I prefer a bigger blade.

For Flat Water I prefer a smaller blade.

But in short, no real big differences between flat water and Downwind paddles. But there is a difference between surfing and distance paddles as stated previously.

thanks for all the replys. Simo I'm thinking of buying a lauhai kai 14" production board. Not interested in buying from overseas love to keep within aus.

mainly used on flat water but very interested dw in the future.