All colors are intended to differentiate different workflows for a consumer. I was confused and started researching about it, in the end, it all came down to Cost Per GB and performance.
This is one of the slowest drives out there but the cheapest. (Apparently, I own two of them). This one was earlier used for archive storage and it still is. But for a poor consumer like me, it’s fine. They are eco-friendly and they also consume a lot less power. Sizes are of 1TB, 2TB, 4TB, 5TB, 6TB. RPM rates as I said are the slowest at 5000-6000RPM (They do not mention on the website but most of the users say so on forums)
These are normal consumer drives. The WD Blue is fast, reliable but makes more noise than the WD Green. It also has an SSHD version with a 4Tb space. These drives are up to 1TB available in 5400-RPM & 7200-RPM Class models. The versions that are 2TB and above are of 5400-RPM. These are the ones for normal PC users.
The WD Blacks are for enthusiasts users willing to shell out any amount of money. Off course, with that money, you get the highest speeds and also are the most expensive. These are mainly focused towards content creators & Gamers. It gives the longest warranty than any other drives of WD. Highest write speed for the WD Black is 227MB/s and the highest capacity is 6TB. These are the fastest consumer drives in the full range of Western Digital Hard Drives.
These Drives are only pushed towards people in NAS (Network attached storage) configurations or in other sense, a RAID setup. They are also performance oriented and their RPM is variable depending on the type of configuration they are in for eg RAID 0, RAID 1, UnRIAD etc. It attaches to your network and helps you to access data on your LAN or Local Networks. They have a 5-year warranty and max speed of the disk spinning is 7200RPM. The highest capacity comes at 10TB.
These are only and only focused at surveillance. They are fixed at a 5400RPM speed and their capacity varies from 1TB, 2TB, 3TB, 4TB, 6TB, 8TB, 10TB depending upon how many cameras and the quality of video you are capturing. It has a 24/7 reliability since it needs to write the video stream from the cameras to the drive. We do not recommend this drive for consumer purposes.
The WD Gold Hard Drives are comparatively new in the market. They are focused at Data Center Storage and High Workload Environments. WD promises 100% reliability on these drives. They are power efficient and work great under load without diminishing the performance. Highest Capacity is again 10Tb with a 7200RPM class.
The Western Digital Hard Drive Comparison is strictly according to research and can change with time.
You can read in detail on the official website here: wdc.com/en-um/products.html