Stepper driver logic input polarity - Mesa 7i96s.

My 'generic' stepper driver data sheet has a 'typical wiring diagram' connected in Common Positive.
 
I originally used (copied from another project) Common Positive, leaving the ENA+/- connections unconnected.
I changed my motion controller and then used the Common Negative connected version of the data sheet wiring diagram.
Is there significance between any of these options for the 7i96s?
What is the importance of making one side (+ or -) common? Is it a 'noise' issue or some other current and/or voltage related issue?
(My steppers are wired bipolar parallel).

null wrote:

What is the importance of making one side (+ or -) common? Is it a 'noise' issue or some other current and/or voltage related issue?

It is the same in every possible way, but that depends on what is driving those inputs, example the parallel port has a bit more current sinking ability than sourcing so using common + is better/safer.
With 7i96S you also have the option of using differential wiring, that is more immune to interference.

Just confirming, is differential connection this simple?
 

Step+ to pulse+
Step- to pulse-
Dir+ to dir+
Dir- to dir-