Whitelines notebooks have pale grey paper with, well, white lines. It's restful for the eyes, and less distracting than dark lines on bright white paper. It's also recommended for use by those with dyslexia. The white lines are easier to ignore when you don't need them, but still visible as a guide when you do.
There's a bonus advantage too. Along with some barely noticable squares in the corners, the pattern can be picked up by a companion app for iOS and Android, enabling you to scan pages into your phone or tablet. The app can then ignore the really pale background, so the lines don't show up at all in your scans, making for a really clean look. The result is that you can bring pages in to your device for storing or sharing, and it looks much neater than a photo of the page would - more like a real scan, but quick and easy to do using just what you already had in your pocket or bag.