WD provides several color hard drives including Blue, Green, Black, Red, Purple, and Gold. WD Blue hard drives are mainly used for general purpose storage. WD Green is basically same as Blue, but it lacks a bit of performance. WD Black HDD is suitable for gamers, media workers, and content creation workers. But it is one of the most expensive HDDs. WD Red is a NAS hard drive. WD Purple is for surveillance. WD Gold, probably the most premium of all, is made for a multitude of Datacenter-specific applications.