Tartan design & fabric weight: Question of general understanding?

[Tobus]

I'm curious about thread count versus cloth weight as well. I own kilts from different weavers, both 16oz cloth, with vastly different sett sizes, even though they seem to have similar sett counts. Is it just the yarn weight that changes cloth weight while using the same threads per inch? Or is the thread density (threads per inch/cm) tighter while using different yarn weights?

My DC Dalgliesh tartan is 16oz nominal cloth and has 270 threads per sett repeat, with a sett size of 7-1/16 inch, or about 18cm. That is 38 threads per inch, or 15 threads per cm.