WD Blue or RED for backup (Data)

I want to buy a new WD 6TB to save my data (Video, Photo Documents) and I am between WD Blue vs WD Red. What are the differences between them?
Which one do you suggest I buy?

Red hard drive WD
WD Red is a kind of NAS HDD with the red cap . It comes with a large storage size, offering a wide range of storage for customers to build a NAS solution. Although WD Red is not designed for gaming, the commonality of home-based cloud storage, SOHO environments, RAIDs, and server investments make the WD Red line worth mentioning.

The WD Red is designed for NAS systems with up to 8 bays and has the power to store your valuable data on one power unit. It can improve the efficiency and productivity of your computer.

WD Blue is a kind of PC hard drive with the blue cover, . Designed as primary drives in laptops and external cabinets, this WD Blue hard drive comes with Hard Drive Capacity that allows you to store high-resolution photos, 4K videos, music collections, and other important files.

This hard drive is also data-dense, indicating that the travel requirement in the header is minimized and the seek time is also reduced. Then the transfer rate would increase.