What is the difference between Western Digital hard drives colors

The meaning of Western Digital hard drives colors:

Western Digital Desktop Hard Drives

WD Blue – Solid performance and reliability for everyday computing http://amzn.to/2dZ2zO8
WD Blue SSHD – Solid State Hybrid Drive http://amzn.to/2dZ2MB5
WD Black – Maximum performance for power computing http://amzn.to/2e33iiD

Western Digital Internal Mobile Hard Drives

WD Blue – Big capacity for portable computing
WD Blue SSHD – Solid State Hybrid Drive
WD Black – Desktop-class performance for notebook computers
WD Red – Designed and tested for RAID environments

Western Digital NAS Hard Drives
(NAS = Network-attached storage is a file-level computer data storage server connected to a computer network providing data access to a heterogeneous group of clients)

WD Red – Personal/Small Office/Home Office
WD Red Pro – Medium to Large Size Business
WD Re – Durable capacity storage for high-availability deployments

Western Digital Datacenter Hard Drives

WD Gold – WD Gold hard drives employ advanced technology to deliver among the best in reliability, capacity, power efficiency and performance
WD Re – Performance-optimized high-capacity storage for high-intensity applications
WD Se – High-performance, high-capacity storage for mid-intensity applications
WD Ae – The maximum capacity energy-efficient cold storage HDD

Western Digital Surveillance Storage Hard Drives

WD Purple – Built for personal, home office or small business surveillance systems using up to 32 cameras
WD Purple NV – Built for Network Video Recorder (NVR) surveillance systems using up to 64 cameras
WD Gold – Designed for medium to large business and enterprise surveillance systems, including mission critical applications, using unlimited cameras

And the last one is Western Digital Green hard drives series:
WD Green hard drives reduce power consumption, provide quiet acoustics, effective power management, low vibration and low RPM.
WD Green hard drives out of production but still available for sale in few places.

For more information please visit Western Digital official website: http://www.wdc.com/en/