Specifically referring to course ratings, not reviews or the content of reviews and,
IMHO...
The difference between course ratings on U-Disc and DG Scene, vs DGCR is: perspective.
More specifically, a local perspective, vs. a national or even global perspective.
U-Disc & DG Scene ratings appear to be highly subjective, emotionally based, and centered around local enthusiasm for a course.
"How glad am I that this course is in my area?" How upset would I be if it were pulled?"
DGCR was created to let people know where courses are, which courses they might want to play when traveling, and even, where they might want to travel to, to play courses. Early on, Tim set the stage by suggesting that reviewers,
Tim said:
What makes a good review[/B]?" when you go to review a course]"Try to judge the course objectively and on its own merits. Not every course deserves a high rating."
I'm sure most of us would be quite enthusiastic to get another course in our area to play, even a run the mill course that doesn't stand out in any particular way. Or that we'd be quite upset if an area course got shut down, even if it didn't make anyone's top 10 list. DG-Scene and U-Disc ratings seem to reflect that sort of emotional response.
I could be wrong, but I don't think even the most avid reviewers on either of those sites, would suggest anyone should take a 3 day road trip to play a bunch of courses with "A" or 4.0+ ratings on those sites. But I think that's precisely what most prolific DGCR's reviewers are saying when we rate courses 4.0+.
Just my take.
Food for thought:
Redit Discussion: UDisc course ratings aren't that helpful.