I too suspect apples are being compared to oranges. The efficiency cited in the article of a thorium reactor is roughly comparable to that of a breeder reactor versus conventional water reactor.
That thorium can be bred suggests the article is taking a highly efficient thorium based breeder reactor and comparing it to a conventional (inherently inefficient) water reactor. I don't have a problem with such comparison if that's what it takes to get beyond public phobias against uranium based nuclear power.
Yes, it must have something to do with the breeder aspect of a thorium based reactor. I have seen this:
The ADTR™ power station uses thorium as its main fuel. As a nuclear material, thorium is not fissile; it is described as “fertile” which means by capturing nuclear particles or neutrons it “breeds” or converts to a type of uranium which is able to react in a fission process and produce energy.
http://www.akersolutions.com/Internet/IndustriesAndServices/Nuclear+Services/NovelThoriumReactor.htm
So, I am just guessing, that thorium will convert to (all?) fissile uranium, as opposed to natural uranium which is only partly U-235?