Are you really out? Like, not conscious of what's going on in the OR during surgery?

I ask because I had an unrelated major surgery 3 years ago where I was only given "twilight sedation" and I was awake for the whole damn thing! I never, ever want to be aware like that again. It was incredibly traumatic. Unlike my colonoscopy, where they knocked me out with propofol but I was conscious shortly after. I'm wondering how is it even possibly to go through something as major as THR with less sedation than a colonoscopy?! Unless the sedation given is like propofol and you're actually "out"?

I understand the pros and cons and am not looking for an explanation of general anesthesia. I'm just looking to better understand from those who have been through "spinal block + sedation" how strong that sedation actually is!

TIA!