That sounds pretty accurate to me, though I must admit that I know very little about either sport. Only ever played a few rugby matches in high school and watched a few games on tv. I find rugby incredibly exciting, and American football boring as hell. It's like rugby, but everyone is so afraid to get hurt that they dress up in more armour than a late medieval knight, and the players apparently lack stamina because there's a break like every fifteen seconds.
Rugby is awesome, a shame it isn't popular here. All you ever see is soccer and bicycle racing, neither of which I find particularly exciting, to say the least.
I like American Football too (played a lot with friends; no coach, no gear, no referee, uneven teams etc.

) , and it takes a lot of planning and teamwork. Imagine it as life-size, contact chess. I especially love how you can tackle people who don't have the ball to protect your own runner. I believe they need safety gear because they way they tackle; in rugby it's more like wrestling the other guy down but in football they collide full speed and if you do that consistently, it's likely you will suffer brain damage even with equipment. Though if it came down to it, I'd still pick rugby.
