To answer your first question: He’s dead wrong. He must have never heard of Hilary Knight, Amanda Kessel, or Hayley Wickenheiser.
To the second: Men have much more opportunity when it comes to professional leagues and play; perhaps the answer here lies in exposure to the public and demand for such leagues. Men have multiple professional leagues across the world: NHL (and minor-pro such as AHL, SPHL, and ECHL); the KHL; major European leagues such as SM-liiga in Finland, Russian minor-pro Russian Major League, the Swedish Hockey League and HockeyAllsvenskan in Sweden (the top two leagues), and the Elite Ice Hockey League in the United Kingdom. And that’s just a small portion!
Meanwhile, Women’s leagues around the world in pro, minor-pro, and/or semi-pro amount to a grand total of 28 leagues. Women are usually, if not always (and I’m not sure on the always), paid much less than a man at any point in the game. The game is growing slowly but sure, though!
Third question: Men and women’s hockey are more different rule-wise and play-style wise, than between the players themselves.
I have played both girls and guys; girls play a much faster and dirtier game. Often it becomes much rougher than a typical boy’s game. Since women cannot body check, we instead use body position to rub out an opponent while battling for the puck and shove them around, the latter mostly along the boards. We also tend to slash, trip, and crosscheck our opponents (mainly because we aren’t allowed to lay them out with a hit… oops!), though most of us have learned to do it discreetly so as not to be caught and penalized.
Another thing about girls/women’s hockey is the play along the boards. We tend to use the boards a lot more than our male counterparts, as I’ve found in both playing and officiating.
I hope this helped!