One other point of comparison has to do with breasts and butts. Or as we say in America, the T and the A.
In American porn, sure we like big tits. But big meaty round bubble butts are the thing here. To illustrate the point, we've had loads of popular American pornstars this past decade with pretty faces, great asses, and small or medium sized, unaugmented breasts. Lily Carter, Allie Haze, and Mia Malkova to name just three. Mia's ass has almost certainly been augmented but not her modest sized breasts.
Anyway, in American porn, if you want to see breast play, you have to watch a boob focused porn series like "boob bangers." In those they may oil up the tits, kneed them, etc. Otherwise, breast play is minimal or non-existent, even if the girl has big tits. But asses get oiled up, jiggled, spanked all the time. And most tease sequences focus on the ass. Not sure if it was "Buttman" in the 90's who started this but it's everywhere now.
In JAV, it's the exact opposite. If it doesn't have a tag like "huge butt" and doesn't show chicks bent over in most of the screenshots, you can forget asses. Even if the girl has a great ass. In one series of vids, there's a chick with big tits and a big ass, always wearing a white shirt and tight jeans. She has come in from the rain and her top is see-through. The camera spends a good minute or more close up on her top, where you can see a floral printed bra through it. Then she goes and bends over to get something from a drawer, taking extra long, because she knows this is supposed to be ass tease. Too bad there's a coffee table blocking her entire ass. Had they cared about teasing with the ass, the coffee table would not have been there. Can you imagine having an object blocking a woman's huge boobs in a tight see-through top? Sacrilege!
I also notice that when they have women strip, they often are not asked to turn around, bend over, etc. It's strange to see a presentation of a naked woman where they just assume you are only interested in seeing the front side of her. In some JAV vids, I can go the entire length of it without seeing a single unobstructed view of her ass, with the only view being during doggy sex when it is partially covered by the guy. If it's the first time I saw the girl, I might not even be able to tell if she has a nice ass or not by the end of a 2 hr+ video.
Not sure why there is this difference in body part fixation between the two cultures. But unfortunately I really like both. I miss all the hot asses when I watch JAV, and miss all the big beautiful tits when I watch American.