Things have changed. Ranger school now has nothing to do with SF (other than rangers are now part of the Special Operations Command). I went through the 21 day Special Forces Pre-Qualification course at Ft. Bragg in 1989. It was the toughest 21 days of my life. I bet I didn't get more than 3 - 4 per hours of sleep per night, on average, the entire 21 days. If that. I will admit, after the 21 days, I decided I didn't have what it takes to be a Green Beret and I dropped out so I ended up spending six months at Bragg working in the 1st SF Training Brigade. Mostly pulling CQ. It sucked being a "leg" at an airborne base.... Since I was there so long, I got to know a lot of the SF instructors. Some of the guys had been in El Salvador when that SF unit got caught up in that hotel back in the 80's and a few of em got killed... do you remember that??
Anyway, I worked with them quite a bit running errands, etc. I asked em who made the worst SF guys and without a doubt, they all said Rangers. Not because the Rangers weren't tough, not because they couldn't handle the load, but because they didn't know how to work as a team AND individually. In SF you have to be able to do both. They had more washouts come from Ranger units than any other units because of that. Rangers train to work as a unit whereas in SF, you have to be able to work as a unit, but be responsible for individual tasks.
As for the berets...
Everybody now wears black berets except SF (green), Rangers (tan) and airborne (maroon).