Both the Waterline and Generation paddle boards from Starboard are very different boards, suited to different water conditions. This great comparison review video by SUPboarder Mag gives a great explanation of both and which one would be the best suited for you.
The Waterline paddleboard shape is specifically designed for flat water paddling in calm waters as this is where you will benefit most from the design elements.
Whilst the Generation paddleboard is one board for every type of condition. The shape of this board allows you to paddle fast for flatwater paddling but has some rocker in the nose shape to perform well in downwind, surfing and ocean paddling/choppy conditions.