While Photos (in your Photo Library) and Web Graphics (in your Web Graphics library) can be used across your website anywhere images are used, the libraries store the images differently, so it might be helpful to know the difference.
Photos stored in your Photo Library are typically taken by club administrators, coordinators, or members. On the other hand, web graphics are usually images created, like a logo, banner, or flyer.
Photos
Photos are managed in the Photo Library. They can be used anywhere on your website images are used, plus you can add them to Photo Albums. Photos are stored in three resolutions: the original size, a "screen size" suitable for web pages, and a thumbnail. When you upload an image to your Photo Library, you can include additional data, like the photographer and date the photo was taken.
Web Graphics
Web Graphics are images uploaded to your website, like logos and graphics, used on the home page, custom pages, and your website template (header, footer, etc.). They are only stored in their original resolution. You won't be asked to enter photographer information or additional data when you upload a Web Graphic. However, you can still add Tags to your Web Graphics.