Passing either of those exams today would earn you the same VCP-NV 2020 certification, so there’s no difference there.

That is as long as you have met the training requirement for the VCP, assuming your current status would include training from the paths here:

VMware Certified Professional - Network Virtualization 2020 (VCP-NV 2020)

Which of the 2 versions do you use? Which are you most knowledgeable in?

The 2.4 exam will retire sooner than the 3.0 version, however there is no public date for that to happen.

What length of time do you think you would need to prepare for the exams?

Those are the factors I would take into consideration if in your situation.