It's all about MISSION. Each unit is trained and geared towards a specific mission to which each performs in an outstanding manner. If you have to swipe with a broad brush you could say that team's (SEAL)guys are a little more vociferous and gung-ho, Army SF a little more cerebral and flexible, Spetznaz a little more ice-water in their veins, SAS are very flexible as well mission-wise with outstanding counter-terrorism training. The Israeli guys always had a wealth of experience under fire because of the circumstances of their geo-political situation. I'd go into combat with any of those guys though, they're truly great at their respective roles and are all top-notch imo. I've always believed in the "quiet professional" moniker, myself.
Can't speak for our British and Isreali brothers but the missions overlap so often now, especially in the Afghan theatre, that it's beyond ridiculous to even try and compare the different units, other than for the sake of having the time-honored c0ck-measuring contests, which are always fun. Lol
The whole concept of the show was just too silly for words. Now lets have one of Alexanders men carrying a 20foot spear, fight a navy seal with an MP5, in a house to house situation.....