I cant explain you the difference in terms of technical behind the scenes issues, but i can guarantee you, that syflex is much, much simpler and quicker than cloth. you basically create whatever you want (polygonal model i.e.) and turn it into a cloth object, a few settings (literally not more than 20) and the thing behaves beautifully.
Learning curve: within 1 or 2 days you will be into it.
Highly recommended!