Well as a practical matter the only thing that changed was the color of the wires.

Years ago a very large, well known, company was doing an huge install for the fed gov. They incorrectly wired every jack and cable to the color code now known as B.

When asked about the change they replied "Uh, it's not wrong', it's, uh, uh, a new standard - yea, that's it - a new standard."

And so here we are today - two otherwise identical schemes except for color.

That's my story and I'm sticking to it.