I am trying to find Bucatini pasta. I don't want the really thick one...I have seen it with #14, #16, etc.Which ine is the smaller diameter?
The number assigned to pastas is particular to individual manufacturers. You would need their data sheet, if they offer one, to know the details based on their product numbers.
On the other hand, many pastas are packaged so that you can see product, and make comparisons. If that is not the case, pasta is not terribly expensive--you could buy a couple of different ones and see which one you like.