It's more because it's 7.6 and it's Been through, more approvals.
Maybe better materials. HK though has good stuff. I've never had an issue with any of their stuff. I do know the battery you're talking about. But not the 7.6 battery. I have 2 of them that I use for my starter boxes. There are 4s though they work well and they're fairly old and they're still are going