You have asked a question that I can answer regarding saddles.
Most better quality american saddles are built on a rawhide covered timber tree,always have a solid ground seat however the swells and cantle will vary depending on what the saddle was built for.
The bigger majority of Aussie style saddles are built on a rawhide covered tree that is made of Queensland hoop pine.
They go by various names but most are commonly called a fender or western stock saddle.
It is a pitty that Hunt 101 is down or I could post some pics of these saddles starting with the tree to the finished product.
I always use a strained web seat in my saddles and in 30 years have never had one fail.
Send me your email address and I will send you some pics of saddles I have built over the last 10 years.
Al