First off, we should explain by saying that deck paint is in fact a type of exterior paint. So we can’t always argue that the two are different…
However, there are some notable differences between paint that’s designed specifically for wood and decking, than the paint intended for the exterior walls of a house.
Deck paint is specifically designed for the kind of wear and tear caused by frequent and regular walking over it. It is specially formulated to avoid the kind of chipping and wearing this would cause.
Paint intended for exterior walls however does not have to have this important feature, and as such may not last as long on your decking as dedicated deck paint would.
So, we would advise that if you were to paint your deck, that you use dedicated deck paint.