The relationship between number of unique domains linking and number of backlinks is interesting when you dive into the analysis.
using this one as an example:
>http://www.penisbot.com/submit_resource.html 7530 (google backlinks)
2,293 unique domains, 22,300 backlinks
2,293 unique domains shows that there are alot of websites linking.. the more unique domains, the more "saturation" or "footprint" coverage a domain is receiving from its linking traffic.
22,300 backlinks shows the number of unique web pages. One website could have hundreds to thousands of webpages that link to the target domain (ie. penisbot). Other TGP could be linking in, and thus skewing the data in a way with a large number backlink stats.
People can also setup lots of domains that have links to the target.
The end analysis is that the more backlinks (web pages) that have links to the target domain, the more chances of traffic flowing through those linking relationships. Each one of the backlink pages has potentials of incoming traffic from SE, from linking relationships, from email, etc.
Looking at the number of unique domains helps put the backlinks number into context, that at the summary level, can reveal if there are some big sites with lots of pages linking and/or , lots of unique domains linking, ... in all , giving a picture of the high or low potential traffic the domain is receiving based on the simple observation (in absense of weblog data), that the more domains linking, the more backlink pages linking to a domain, the more potential traffic that site is receiving.
Since the t3report shows exact domains and webpages, you can fine tune your analysis with real linking data.
Fight the FYI!