Photos uploaded directly on the Photos page should relate to the project as a whole or to non-selection item related topics. These might include photos from a pre-construction walk-through or progress photos taken throughout the job.
Photos added to the Specs & Selections are more commonly related directly to that item. For example, providing your client a photo of each kitchen sink that you've priced out as an option. This allows your client to see those specific photos when reviewing that option rather than having to search for them in a separate page of the project.
You can however, see the photos attached to the Specs & Selections page, plus photos attached elsewhere in the project by clicking the “Attached Elsewhere” link in the filter box on the right side of the project's Photos page.