A very quick reading makes it pretty clear. The "True" one was in 2008, and based on the law as it was written. The second was in 2013, and based how it turned out after it met the real world.
The 2013 article outlines this process pretty well - the whole thing is worth reading. But a good pull quote: Yet Obama repeated "if you like your health care plan, you can keep it" when seeking re-election last year. In 2009 and again in 2012, PolitiFact rated Obama’s statement Half True, which means the statement is partially correct and partially wrong.
This is exactly the problem. They made some predictions about the law (which turned to be completely wrong, but that's not even the point) and tried to pass it as "objective fact", not as their private conjecture, implying that those that disagreed with it (and turned out to be right) are just lying.
This is the exact opposite of objective fact. This time they got caught because their predictions didn't come true and their subjective opinion disagreed with the facts so obviously that they were forced to flip. But many other times they do not get caught because there's no such sharp contrast between their private opinion and facts, and you can always muddle the waters and spin the arguments to try and present why your opinion is "objective truth" and anybody who thinks otherwise is just "truth denier".
As a political propaganda, it's fine - everybody tried to prove their opinion is correct and the other guy's opinion is wrong. But it takes special kind of hutzpah to call one's opinion "objective fact" and try to paint all the other opinions as lying. Exactly the kind of hutzpah the "fact checker" sites are swimming in.
TBH, it doesn't even have to be a different politician - here's Obama saying famous "77 cent on the dollar" and gets "mostly false" http://www.politifact.com/truth-o-meter/statements/2012/jun/... here is essentially the same getting "mostly true" http://www.politifact.com/truth-o-meter/statements/2014/jan/... Did women pay drop significantly in these two years? Probably not. If you read the conclusion, it's saying practically the same thing - yes, raw statistic is saying that, but it does not mean what people quoting it mean (that women are routinely discriminated in pay - i.e. maybe they are, but that specific statistic does not point to that conclusion and should not be used as an argument). But one time it gets "false", another time it gets "true". Why? Who knows. Certainly very short of "objective truth".
And then there's this: http://www.politifact.com/truth-o-meter/statements/2008/oct/... Yes, the famous "if you like you health plan, you can keep it". Rated as True. Or is it "Lie of the Year"? http://www.politifact.com/truth-o-meter/article/2013/dec/12/... You can read the whole evolution of this "objective truth" here: https://www.forbes.com/sites/theapothecary/2013/12/27/in-200... I think this objective truth is a tad less than objective.