When you're looking at Your Schedule on your drafts page, Tailwind shows you a preview of what your pinning schedule would look like if you were to add your drafts to your queue.
The full-color thumbnails in Your Schedule are pins that you have already scheduled. These will be pinned to Pinterest when their scheduled time comes.
The grey, slightly transparent thumbnails in Your Schedule are your drafts. They simply show you what your schedule would look like if you were to add all of your drafts to your queue. These won't be pinned at the timeslots that they're in, unless you schedule them!
You can confirm this by hovering your mouse over the grey thumbnail, and seeing the DRAFT label.