The rating is higher for the B1G, the total number of viewers is slightly higher for the ACC.
I'm 99% sure this is how it works, been a couple years since I read about the methods...
The Household rating is based on TV households, not the number of viewers. So two people in one house count only once. The 2+ is total viewers that are 2 or older, and the Adults 18-49 is total viewers in that range. I'm pretty sure the real comparison that the conferences would care about would be men 18-34 and men 18-54 - the demographics your advertisers are trying to reach.
I'm not sure how they estimate/calculate the number of people per TV.
It's also interesting to compare to last year...
ACC: goes from 1,226 18-49 and a 1.66 (UVA vs UNC) to 1,400 and a 2.03 (Duke vs. ND)
B1G: 1,096 and a 2.18 (Mich St. vs Purdue) to 1,268 and a 2.29 (Michigan vs. Wisconsin)
SEC: goes from 1,118 and a 1.94 (Kentucky vs Texas A&M) to 1,021 and a 1.64 (Kentucky vs. Arkansas)
Big 12: 896 and a 1.53 (WVU vs. Kansas) to 851 and a 1.35 (Iowa St. vs WVU)
It's tough to draw conclusions off of a small sample, but in terms of prestige of the matchups, obviously the Big 12 saw a drop and the ratings went down slightly. The SEC saw a drop in the same way. Also the ACC may have gotten a bump from Duke/UNC playing in a semi-final and hooking people into the tournament to tune in the next day. They were the most-watched ACC semifinals ever.
I doubt the TV ratings have much of anything to do with being in Brooklyn, although you might figure it gets a slight bump among NYC households. You'd have to hold it there every year to build up an audience off of the prestige factor like the Big East at MSG.
