the "BUN" part usually means that the item is part of a "Bundle" meaning it is sold in a combination with other items. The "=" sign at the end usually means that the part is a spare, it is not sold as part of a configuration but as an extra item to replace a failed item.
BraovCalos is correct, it just depends on how you plan to order the Supervisor
BUN= Usually included as part of a bundled part number, I.E. comes bundled with the Chassis, Power supplies, and fan modules. = = This you are ordering as a spare part where you have an existing N7K with one Sup and you want to add another. -= This usually as some type of name convention after it like N7K-SUP1-8GBUPG
By the way SUP1 has reached end of life and is no longer orderable except for memory upgrades.
