Model number description

1 - Can you tell me what the difference is between these two model numbers please

Western Digital 4 Tb Hard Drive PN:WDBBGB0040HBK-NA

WD My Book Desktop Storage 4TB / PN:WDBFJK0040HBK-04

Or to simplify what does BBGB and BFJK mean?

2 - what is the disk format for each?

Thank you

IIRC, BBGB is the newer version of the BFJK.

They’re NTFS out of the box, but you can reformat it however you like.

Thank you for your response TonyPh12345
1 - I have a Netgear Nighthawk R7500. Netgear says it will work with the WDBFJK0040HBK-04. Yet this is no longer available from WD. They do not list a replacement on their web site. WD tech recommended and Amazon however does list the WDBBGB0040HBK-NESN as a replacement.
What does BFJK and BBGB stand for?

2 – I purchased a WDBBGB0040HBK-NESN and it will not work with the Netgear.

What is the difference?

The letters don’t stand for anything. But all of WD products use a similar model number scheme. A computer database probably assigns them when the development of the product begins.

As to the differences, I have no idea.