What's the difference in these fuel pumps?

[hot440roddin]

So as the topic states, what is the difference in these pumps? I am using Summit Racing url's for reference....
1: http://www.summitracing.com/parts/CRT-M6935/
2: http://www.summitracing.com/parts/CRT-M3672/
3: http://www.summitracing.com/parts/CRT-M4845/
4: http://www.summitracing.com/parts/CRT-M4589/

I'd imagine that what ever the difference may be right in front of my face and I'm not seeing it, so I thought I'd ask rather than sit here are try to figure it out... Btw, motor is a 440 that will have an 850 cfm double pumper carb and a Lunati Voodoo #60303 cam kit.

Or would one of these be the better route:
1:http://www.summitracing.com/parts/CMB-03-0058/
2: http://www.summitracing.com/parts/CMB-03-0059/
-There was another kit like the above two but it also included a carb fuel line... I am wanting to try and use another fuel return line in hope to help with any potential vapor lock... I am also planning on using a new factory style fuel tank..

[burdar]

The difference is where the inlet and outlet fittings are located. 

[mojavered]

I think that the 4589 might be only a 5/16" inlet?