This argument keeps on surfacing, doesn't it? The difference in mean ratings depends on so many factors, that engaging arguments can be had regarding its causes until the cows come home (or perhaps even longer than that).
For grins, I'll add my datum: 1600-ish in Live, 1900+ in Online.
But regarding the title of this thread, I don't play turn-based (any more) because I can't remain interested in any single contest for more than 30 minutes.
The average rating in live chess here is ~200 below that of turn-based. I suspect that the most significant cause, but not the only cause, is that live chess here appeals to more casual and weak players, while it fails to appeal to serious and strong players.
No. This makes no sense. The average live rating is actually much much deflated from the average CC rating (by about 400 points).
However a 2000 CC player is not a 2000 USCF player, and when said player goes to live he's often somewhere between 1600-1700.
That's because there are more strong players at lower levels in LIVE CHESS and USCF chess.
I'm using data, not impressions. The difference is 200, almost exactly. My data is accurate, as is my analysis. I've stated clearly that ratings cannot be compared; all assertions rooted in comparisons must first establish that there is a basis for comparison.
"Strong" is in the mind of the beholder. When FIDE grants a title, the recipient should be regarded as strong by all those without the same or higher title. I see few FIDE titled players in Live on this site (the strongest I've played is a weak FM--he earned the title in his youth and no longer plays OTB actively). I have played a FIDE titled GM in turn-based who is in his prime and still improving in OTB.
Live standard:
Rating Distribution
Live blitz:
Rating Distribution
Turn-based standard:
Rating Distribution
1384