[Roadboat24]

If nothing else, it shows the impressive effect achievable with stacked images.
Thanks Kobie or an eye opening demonstration. ..

[Marktax]

2 is the stack, clearly indicated by the repetitive boat wake. The objective of getting the falling water to smooth into the white fluffy look is achieved identically in both cases, but the ND shot does better justice to the river below because it did not fully smooth out the turbulence, which remains dramatic.

I use a combination of a polarizer, maybe on top of an ND 2 or 4, and fewer multiple exposures than 30 -- say, 7 or 8 1/8th-second exposures. The hardest thing with white water is not blowing out the whites, which often means shadow boosting in post.

[stevebrot]

but the ND shot does better justice to the river below because it did not fully smooth out the turbulence, which remains dramatic.

...therein is the big difference between the two techniques. The blur with the ND represents the full exposure time, whereas that of the composite has gaps and is a approximation making it difficult to finesse the quality and amount of blur.

[Kobie]

If nothing else, it shows the impressive effect achievable with stacked images.
Thanks Kobie or an eye opening demonstration. ..

No problem. I'll probably do another one with my buddy but this time, we're going to use the same lens as well.
We had bantered back and forth here and there about the differences. We realize that realistically, there isn't THAT much difference between the two outcomes depending on your settings.