In terms of detail, do remember this is just concept art- the artist goes into as much detail as he cares to do, he can afford to make it as richly drawn as he wants so that he expresses the style he has in mind and perhaps gives inspiration to the people actually creating the models, but that doesn't mean we can use the concept art to guess how detailed the in-game models will be. I could be wrong, but also notice how there are just one or two men in the pictures either on or next to the ships, as if for scale. If the artist had been asked to come up with something for practical use in the game, I would have thought he would draw particular parts of the ship close up and from a 3D/isometric perspective, with sailors positioned on the deck.