First, what is the difference, other than the number of buttons, between a five button and a six button traditional waistcoat for a kilt?

Next, how do these differences affect the neckwear or any other accessories being worn with the waistcoat?

I'm guessing that the six button waistcoat has a higher neck line than a five button waistcoat... So how does a higher neck line (I think called Edwardian style) on the waistcoat affect the type of neckwear that should be worn?

Thank you.