In college, an Aussie rules footballer joined our American football team. Georgetown University's team is no where near the level of the big D 1 schools, but we had fun and had some pretty tough players.
During his first few days playing against us we were just in "grays" (t-shirts and shorts) and helmets. He did not understand the big deal was regarding American football, and when he asked about it he was cool and not a jerk. You could tell he was curious. We just told him to wait and he would see.
Then "Crunch Day" came. This is the first day in full pads which seems like a series of gladiatorial combats, and I was his first opponent. I hit him so hard (and he was so unprepared for it, really) that I could read the Nike off the bottom of his cleats as he flew through the air. I truly am not exaggerating. All I remember before we collided was his hesitation as he tried to grapple me instead of launching himself at me.
When I helped him up I asked if he understood now, and he just said, "Holy sh!7!" as he mocked my Southern drawl. After Crunch Day he had a concussion and hung up the pads for good. When I asked him about it, he said something like, "You guys are like missiles. I can't believe how hard you crash into each other. You have been doing it since you were kids and there is no way I can catch up." What I remember is that this was said like he had just completed an experiment and not "failed." I think that is when we really respected him and never questioned his decision. Even though he stopped playing, he watched us play and practice often, and definitely came drinking with us a lot.
Later he did say, "In the spring you need to come out for a real man's sport and I will teach you how to play rugby." (We didn't have Aussie rules so he had to make do with standard rugby.)
I took him up on it, and had almost the exact mirror experience. For a couple of practices I did pretty well, but it required a lot of thought not to act like I had pads on me. One day a guy broke free from the scrum and I took the appropriate attack angle like I would have playing middle linebacker. At the very last moment it flashed through my lizard brain that I was about to make a perfect form tackle for American football, which at that time meant I would put my face right in the center of his chest. That would have been fine if I was wearing a helmet, but you don't wear helmets in rugby, right.
I was able to adjust right at the last second before the collision, but still hit the guy pretty hard. Knocked the wind out of him and nearly separated my shoulder. That was the day I decided it was too late to break old habits and learn a new contact sport.
Aaron, was the guy's name and I heard he later played a few years of professional Aussie Rules Football when he returned down under. I really liked him and think of this experience often. I think we were both so curious about the differences that we became really good friends for that year. Then I lost track of him, and that was 23 years ago now.
For me it is like comparing boxing and wrestling or trying to understand fighting an armored knight. It requires a different style and different toughness, but they are both brutal and dangerous if you don't know what you are doing. I just would not want to be a beginner taking on someone who has done it their entire life. It also makes me think of Hollywood and how "beginners" beat experienced warriors. I know Hollywood sells fantasies, but it still annoys the crap out of me.