I've got an ill feeling coming on, I agree with this Nate (except for his opinion that NFL is tougher... and his sense of velocity LOL).

He's actually correct; NFL players collide into each other with much more momentum, often blindsided and they really do need those elaborate pads. It has nothing to do with any sport being 'tougher', it's just inherent qualities of the two codes. If Rugby players tried to play American football with no pads many of them would be in hospital pretty soon.
In Rugby you TACKLE from front on and you don't need those hits to stop a man, while in American football they just collide at full speed.

IMO Rugby should have a headgear for the backline. Not a crash helmet like in American football but something similar to that worn in amateur boxing to prevent impact concussion injuries. Those shoulder pads and body suits are just gimmicks, soccer shin-pads are more useful. And only forwards need those scrum caps.

Soccer is for kids, Football is for *******, rugby are for men.

Questions like this are difficult to answer, because they usually indicate that the asker is basically unfamiliar with one of the sports involved in the comparison. First of all rugby players do wear pads -- just not the rigid plastic sort that gridiron players use. The rule in rugby is that the material must be soft, and no more than 1 cm uncompressed. You can find all sorts of thigh, shoulder, kidney and chest protectors available for rugby players within that rule. A lot of us (particularly the forwards) wear shin pads as well.

First of all there are very few substituions allowed in rugby -- you dress 23 with 15 starters all substitutions are generaly permanent. This means that at least 7 of starting players must be on the pitch for the entire 80 minutes. There are a lot fewer breaks in play as well. Believe me, after 75 minutes of running up and down the pitch and when you are into your seventh or eight mile, you are going to notice the extra weight from those rigid pads, and they are going to be interfering with your ability to run as well. You are also going to be having a lot of difficulty losing heat -- particularly if you are wearing an American style helmet. Heat stroke would be a real risk.

It is also important to realize that the nature and purpose of tackling (and more importantly rucking) in rugby is fundamentally different than in gridiron. In gridiron you want to stop the runner cold -- to not give up a single inch more than necessary -- because of the downs for distance system and the uncontested breakdown. A few inches can mean the difference between keeping or losing the ball So you hit the runner as hard as possible in order to kill his momentum. The position you end up in after the hit doesn't really matter, because once the runner is down, the ball is dead.

Not so in rugby. After the tackle the ball is still live -- a player off his feet must release the ball and make it available for some other player. As a result, the purpose of the tackle in that rugby is not so much to stop the runner (albeit that is generally a good thing) but to place the tackler in a position where he can remain on his feet and poach the ball. If you can flip the runner so that the ball is on the wrong side of his body, for the ruck so much the better. Similarly, the purpose of the ruck is to make the ball available to a teammate. Either way, you don't (in most circumstances) want to commit to the all-out charge or hit because it means that you can't stay on your feet and compete for the ball.

The laws are different too -- in rugby you can't lead with your head, leave your feet, or shoulder charge. You must make some attempt to "wrap" up the runner with your arms when making the tackle. Again, it makes the rigid padding less necessary.

One should also consider that the padding and especially the helmets may actually add to the danger as players (with a false sense of security) will tend to hit recklessly. Rugby certainly doesn't contend with the degree of deaths, crippling injuries and concussions (and early onset dementia that follows) that gridiron players experience.

Edit: as Pearce B. pointed out below, the flexibility factor is also important, which I hadn't considered. The rigid padding would definitely interfer with getting into the proper body position to ruck or poach the ball after the breakdown.

I can't answer this question any better than blm did. I'll just say again that it's simply a difference between the sports. Pads would severely inhibit the range of motion required for rugby, while football players without them would literally get killed. It's not a question of "manliness," like some answerers seem to think, I've seen football players break their arms mid-play and still manage to fight their way to the end zone, play 3/4 of a game at quarterback with a broken throwing hand and still be effective, break their finger bones in two, go to the sideline, tape them straight and finish the game, and so on and so forth. I'm completely sure rugby players have done similar things. I wouldn't call either game "tougher," different games just require different equipment. Rugby would suck with pads, football would suck without them.

why would the hits be harder?
they dont get injured as often as you think, you cant tackle the players head anymore

why would they wear pads anyway? thats what americans do..even womens rugby dont wear pads lol