Yes, they are fundamentally different, for a number of reasons, but one of the main ones is that parody political speech in publications consists mainly of well-established "fair use" exceptions to copyright law. In Campbell v. Acuff-Rose, SCOTUS Justice David Souter wrote that "like less ostensibly humorous forms of criticism, [parody] can provide social benefit by shedding light on an earlier work, and, in the process, creating a new one." Merely screwing with a trademark does not involve copyright law one bit, does not "shed light on an earlier [copyrighted] work and create a new one in the process," and thus is not covered under "fair use" laws.
But I have a question for you. Would your opinions be the same if the T-Shirts were attacking the Clinton News Network in the same fashion?
Sorry, PL, but this suggests to me that you haven't actually read the article or my response - or at least haven't read them very closely - because both the article and my response make it quite clear this company IS offering an anti-CNN t-shirt. The article mentions the CNN shirt in just its third sentence.
And as I already indicated in my original response, my feelings are exactly the same regarding this shirt. CNN will be legally forced to send out a cease-and-desist order to protect their trademark, whether they want to or not. I have no opinion on the CNN shirt itself other than to say that it's deriviative and lame, and you'd think they could come up with something funnier.