Col Doug Drysdale’ son Collin was my YO Course Officer when I joined. Col Drysdale and 41 Commando were awarded the US Presidential Citation for their part in the retreat from Chosin Reservoir with Task Force Drysdale. The Corps links with the USMC is indeed a strong one.
The RM are a much smaller force prob more akin to US Army Rangers. They can be more selective in their recruitment and set higher standards than the USMC.
But the USMC prob has the edge on weapons handling and psychological pressure inflicted upon their personal. You folks can beast the shit of your people and run them into the ground...
The USMC is a middle weight force but it can come up with a combined arms team, where as the RM are prob more on the lighter end of the spectrum.
But either way it really does not matter because with enough Armor and ass both forces would be pummeled by the US Army. A Stryker Brigade or an Armored Brigade would be quite the challenge for a light infantry force to hold off.
And the UK etiquette confuses me (though adapted to it) - you have the steering wheel on the right side, drive on the left, supposed to stay on the right on escalators, eat using your fork on the left etc etc.
I have a simple mind - just do everything on the same side!