At least in our families, I've found the parents have much more of an issue with comparing our kids to theirs than the kids themselves. The kids find common ground and just have fun, whether it's playing a silly game like Apples to Apples or taking a hike outside. The real minefields are dancing through the whole sharing latest news without bending anyone's noise out of joint.
I find the hardest is when one of them has a child who is good at something and wants to rub your nose in it, if somehow by producing children with gifted IQ's, one automatically wishes ill on the rest if society. One niece is graduating top of her class with honors galore and a full ride scholarship secured for next year. Every time we're together, the mom asks, "And where did so-and-so graduate after being in the gifted program?" - knowing full well he wasn't anywhere near the top. I usually ignore the comment and go back to being excited for my niece, because I am proud of her hard work and commitment. And moms aren't nearly as competitive when they think their kid bested yours.
But it doesn't really get under my skin. I think that's the key. If it did, I probably would say something that would start a family feud. The way I see it, our values of wanting our kids to do what they're passionate about is different than theirs, who want their kids to go into specific fields of study. I'm not going to judge their choice, because it's what they've chosen for their kids, and they'll live with the consequences of the choices. I'm too busy living with the challenges of my own parenting choices to ever feel superior.