Question M.2 Compability messed up ?

[BozhidarK]

So basically I am building an ITX system and I'm using an MSI B450I Gaming Plus AC. In the manual clearly says M.2 2280 (key M). I couldn't find a lot of M.2 with this kind of key so I looked up some builds. And I see people putting a WD Blue 500 GB M.2 with and B & M key. Am I missing something here ?

 

[Dark Lord of Tech]

1 x M.2 ports (M2_1, Key M)

• Supports PCIe 3.0 x4 (AMD® Ryzen 1st and 2nd Generation/ Ryzen™ with Radeon™ Vega Graphics) or PCIe 3.0 x2 (AMD® Athlon™ with Radeon™ Vega Graphics) and SATA 6Gb/s 2280 storage

Is compatible:

PCPartPicker part list / Price breakdown by merchant

Storage: Samsung - 970 Evo 250 GB M.2-2280 Solid State Drive ($97.99 @ Amazon)
Total: $97.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-03-18 09:45 EDT-0400

 

[BozhidarK]

1 x M.2 ports (M2_1, Key M)

• Supports PCIe 3.0 x4 (AMD® Ryzen 1st and 2nd Generation/ Ryzen™ with Radeon™ Vega Graphics) or PCIe 3.0 x2 (AMD® Athlon™ with Radeon™ Vega Graphics) and SATA 6Gb/s 2280 storage

Is compatible:

PCPartPicker part list / Price breakdown by merchant

Storage: Samsung - 970 Evo 250 GB M.2-2280 Solid State Drive ($97.99 @ Amazon)
Total: $97.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-03-18 09:45 EDT-0400

I know this one is compatible I am asking why the WD Blue M.2 Is compatible since it is B + M and the board is only M

 

[Dark Lord of Tech]

Because It's B+ (and)M. Also those WD drives aren't worth using as they are no faster than a standard SATA III drive. I don't know why they even sell.

 

[BozhidarK]

Because It's B+ (and)M. Also those WD drives aren't worth using as they are no faster than a standard SATA III drive. I don't know why they even sell.

What does B+ (and) M mean and how do I know which to put in my board ?

 

[Dark Lord of Tech]

View: https://www.youtube.com/watch?v=SP0Brsc0dMY