Well ya. The capitalization matters. One refers to a major political party that is recognized in all 50 states and the District of Columbia. The other has nothing to do with political parties whatsoever. But fine. Let's not quibble over such matters. We'll move to substance.
Rand Paul, just for example, has publicly declared he is not libertarian (source:
Rand Paul Leads GOP Kentucky Senate Race as Outsider - TIME). Sure, he's infinitely better than McCain, Lindsay Graham, and the majority of the lot. But he's not libertarian. He wants to be president and will be whatever he needs to be in order to achieve it. Hell, he will be an Indonesian street whore if the money is right.
His TSA "reform" proposal was complete sh!t, not libertarian at all.
Hell, even Gary Johnson, a closet statist who ran as a Libertarian last election, at least proposed, what, a 40-and-some-odd percent cut in spending? Do I have the number right? There were some fairly significant cuts from what I recall.
Meanwhile, the mainline Tea Party is redefining what it means to be libertarian so that they can appeal to a broader base, while keeping the gravy train (Koch money) rolling in. The Tea Party has nothing to do with small government.