Forgot the difference between white and blue cable

I just received a 2001FP to replace my broken 2000FP.

Forgot why I used white connector instead of blue.

What is the diffence between them?

 

Also this monitor has USB connectors on the back and on the side. They sent me a USB cable. What do I do with it?  What does it do?  How do I connect it?  Do I need it?