There are several ways to distinguish the difference but most would require some sort of benchmarking program. In many cases, people won't be able to see much difference between Intel and AMD. It was different a few years ago when that was more obvious. One of the biggest differences though that has been mentioned here is the price. If you can get an equivalent processor for a couple hundred dollars less, then why wouldn't you? AMD processors are just as good, if not better in some circumstances, as Intel processors.
With that said, I chose AMD as that's what I use and what I prefer.
