First of all, just to be clear, you cannot purchase the NUC8i#BEB boards as standalone board products. They are only sold as part of a kit and come preinstalled in the chassis. Only the VPro boards (NUC7i#DNBE, NUC5i#MYBE) are available for purchase as standalone board products.
Only the NUC8i#BEH or NUC8i#BEK chassis can be used with NUC8i#BEB boards.
See here for information on available NUC boards: https://www.intel.com/content/www/us/en/products/boards-kits/nuc/boards.html
See here for information on available NUC kits: https://www.intel.com/content/www/us/en/products/boards-kits/nuc/kits.html
See here for information on available NUC systems: https://www.intel.com/content/www/us/en/products/boards-kits/nuc/mini-pcs.html
Hope this helps,
Note: '#' can be 3, 5 or 7 for Core i3, Core i5 or Core i7, respectively.
Note: NUC systems are complete, with memory, storage and Windows 10 preinstalled.
Thanks for the answer. The reason I originally asked was because I saw this in several shops: