KB:

If you're comparing how Size 100 silk wraps compared to Size A nylon, it will be easier to avoid gaps and the dreaded over-wraps with the larger diameter thread.

Personally, I've never noticed much of a difference in wrapping silk vs. nylon of the same approximate diameter. The silk can be fuzzy at times, but that's about it. I usually use silk just because of the wide array of colors available. It's very difficult for me to tell the difference between silk and nylon, especially when not color preserved. Even with CP, it's hard to tell. However, if I use shellac as your CP, I notice that silk has more sparkle, especially in the sunlight.

BTW, the diameter difference between Gudebrod A and 00 is that the A is about 20% thicker than the 00. Prove it to yourself. Mark off a fixed distance on a dowl and count the number of wraps it takes to cover it.