Fishing Line Diameter

[anchor man]

I was looking at some of the new Stren Suffix and Berkley Maxx lines today in 6lb test. I noticed the line diameter is about the same as the diameter of the 10lb test line of their more standard (castable style) lines. Is the durability and strength of their 6lb line merely based on beefing up the diameter and called it a tough line. I know there's surely more to it than that, but isn't the purpose of using lighter lines mainly for a smaller diameter?

[upnorth]

That would be my thinking.