It isn't much of a difference.
But, instead of buying watch bands over and over that I will probably won't use that much.
I have decided to buy just 16mm bands for both my 16mm and 18mm watches.
For the most part.
My G-Shock GW5600J-1 looks better with different color bands.
But, my Citizen Eco-Drive BM8180-03E looks better with black bands, but to change it up alittle bit.
I might put a 16mm band that isn't black on it for a day or two instead of buying more 18mm watch bands.