Oh geeze, I'm not an expert in this stuff. I'm writing a novel about a PhD-level biologist (who becomes a shapeshifter) and ended up doing loads of research about biology... stuff in order to make the way he modifies people a bit more believable (so many stories are so full of hand waving these days it drives me nuts!).

One of the things I ended up researching was sexual dimorphism in various species including humans and wow what a rabbit hole that is! I have in my notes all sorts of things (differences) that most people have no clue about:

• Women have different livers. Specifically, estrogen/testosterone turns on/off epigenetic pathways that make their livers behave a bit differently. So if a woman receives a liver transplant from a man or vice versa, it'll be a while before it starts behaving "on brand" haha.
• Women's hearts are bigger/stronger/thicker but most people know that (necessary for pumping blood for more than one!)
• Women's internal organs can move around a lot more than men's. They're not fixed in place like with men. Along these lines, women's tailbones can move a little bit (men's might as well be hard stone). This was important research because my shapeshifter character gets requests to give people tails and I needed to know if that was even possible and, come to find out, much simpler to give women tails than men! Haha
• The tendency for women's brains to form more cross-hemisphere connections VS men's tendency to form front-to-back connections is actually a very funny part of the story (it's a comedy). Anyone that reads that part (and doesn't understand what it means yet) is going to be thinking, "holy shit that makes so much sense!" Hahaha
• Women can perceive textures men cannot. The reasons why aren't complicated: Thinner skin, smaller fingers means greater nerve density and sensitivity. This was the research that had me looking into nerve pathways and why women are just generally more sensitive than men. Besides what I already mentioned, women store fat completely differently than men. Essentially, men and women have completely different flesh. Men cross-link fat cells making them much more "solid" whereas women stack their fat cells on top of each other like little pillows... This is why they're softer than men.
• Now combine the flesh knowledge with the T-cell nervous response and the fact that stacked fat cells (and the vasculature that goes with that) together and you end up with this: Women bruise much easier than men. Bruising results in a cytokine (swelling) response... Which amplifies pain in the affected region. Having more lifelong exposure to cytokine in various joints that are constantly being used/bumped, it makes sense to me that women would be more susceptible to inflammation-related pain disorders such as rheumatoid arthritis. Which impacts women at two to three times the rate of men!

Hopefully that explains what I think I understand about the differences that lead up to women experiencing pain differently/more intensely.

...and that's just scratching the surface of all the differences! People think men and women "are basically the same, just with a few physical differences" but it's more like this: Men and women experience the world completely differently from each other.

Women physically see things differently than men (they see colors in greater resolution), they feel the world differently from men, and they have 50% more olfactory bulb neurons than men which means they have much more sensitive noses (especially to certain compounds like sulfur and scents like lavender have a vastly enhanced effect!).

Women live in a different world than men. We need to stop pretending we're the same and start accounting for it in medical studies!