I just got back from the US (British citizen) and a couple of years ago I went to Israel to visit my then-girlfriend (now wife).
TSA wasn't as bad as I thought and even though we both requested not to go through the scanner the staff were polite and professional (this was at El Paso, and later at Orlando-MCO). I've had more, erm , invasive patdowns before and they explain everything. However, it seems to me that they give the same level of scrutiny to everyone.
Flying to and from Israel (on El Al certainly) there's a level of profiling. They come through the check-in line "chatting" to people, looking for holes in their story and subconscious giveaways that they're lying. Me, I lived in Saudi Arabia for years and had Egyptian stamps in my passport, so I was deemed in need of a few extra searches, but nothing out of the ordinary. My wife, on the other hand, an Israeli national, gets basically no questions when travelling back. Again they were very professional, even friendly.
So, I'd say the US system is pretty thorough with everyone, whereas Israeli security find out early on if you're a person of interest and if you are, they take a bit more time to "chat" to you.