Yes, they are, and those differences actually play in the favor of women as strength and explosiveness are even bigger factors in grappling that it is in striking. The reason why you don't see grappling comps between men and women is the same reason why there are gender categories in non-contact sports like snooker, bowling and badminton.
I've seen women grapple and wrestle against men.
Males and females train and spare together on most high school wrestling teams in North America. Not so long ago females and males were competing against each other fairly often in the US in smaller districts without enough female wrestlers to make a bracket. Some did quite alright.
The differences you point out are very real, and I'm not dismissing them.
However, if there's a significant margin between skill level, and the female has some grit, it's possible to overcome these differences, and it does happen.
Women beat men at grappling and wrestling tournaments all the time.
Usually it looks something like this:
[YT]watch?v=3HVkO_JwP9w[/YT]
But occasionally you get something more like this:
[YT]watch?v=uGvrX4wnjEQ[/YT]
And yes, these are outliers. I know that.
Generally, it's not going to be great. But on occasion, if the skill level gap is wide enough, it can be interesting.
That said, my sense is that someone like MM would tool RR pretty badly. But someone like McCall (who's grappling pedigree is limited to high school wrestling a pretty limited amount of college wrestling), I'm not certain about.
That's why I'd be interested in seeing it happen. Not because I'm confident RR would win, but because I'd just like to see what would happen, see how competitive she might be, or if she wouldn't be competitive at all, or if she might actually pull it off.
No harm in a match like that except the fear of someone hurting his/her ego. S'all I'm saying.