I can illustrate this in a simple way that's backed by common understanding of the public positions of the two candidates.
Let's take a look at the typical gay San Francisco male. He is overtaxed, has many of his rights violated on a daily basis by the federal, state and local governments, and seeks more freedom for himself and his family.
How do Paul, Kucinich, and a typical Libertarian candidate stack up on his liberties?
Ron Paul:
1) Ron Paul would vote to lower his federal taxes (but would have no opinion about his state or local taxes). Generally economically libertarian.
2) Ron Paul would vote to overturn Supreme Court rulings eliminating sodomy laws, claiming that states have the right to imprison the gay San Franciscan for "immoral activities" if they so choose -- regardless of the Bill of Rights. Civilly authoritarian, with a pastiche of "constitutionalist" gobbledygook.
3) Ron Paul supported the DOMA law that ruled that the Full Faith and Credit Clause of the Constitution does not apply to marriage licenses, and that created a federal definition of "marriage" that permanently excluded the San Francisco gay man. Civilly authoritarian.
4) Ron Paul supports a state's "right" to revoke parenting credentials upon crossing a state line. If the unlucky man was to cross the Oklahoma border, he and his partner would both be declared legal strangers to their son. Civilly authoritarian.
5) Ron Paul would vote against a single-payer socialist medical system. Economically libertarian.
Dennis Kucinich:
1) DK certainly likes high taxes. Economically authoritarian.
2) DK supported the SCOTUS ruling in Lawrence vs. Texas. Civilly libertarian.
3) Kucinich voted against DOMA. Civilly libertarian.
4) Kucinich upholds the full faith and credit act of the Constitution in parenting as in other areas. Civilly libertarian AND more "constitutional" than Ron Paul.
5) Kucinich supports a single-payer socialist health system. Economically authoritarian.
Typical Libertarian Party candidate:
1) Would of course vote against higher taxes. Libertarian all the way, baby!
2) Supports the SCOTUS ruling out of an understanding of the Constitution, but also out of a commitment to get government at all levels out of the business of dictating people's lives. Thus more libertarian in outlook and rationale than either Paul or Kucinich.
3) Opposes DOMA for the same reasons as #2, and supports equal marriage treatment as a step to getting government out of the marriage business altogether -- thus more libertarian than either of the prior two.
4) Opposes Oklahoma's "right" to revoke parental rights by fiat, regardless of "states' rights" concerns. Puts individual rights first and wraps them in a full-faith-and-credit rationale. More libertarian than RP or DK.
5) Opposes a single-payer socialist health care system -- once again, libertarian.
Now, where would all three likely agree on issues of importance?
1) Wars -- all three want out of Iraq (and likely, Afghanistan). All three support major drawdowns of forces deployed in overseas bases.
2) USA Patriot Act -- all three opposed it.
3) Ending the Federal drug war.
Obviously, the Libertarian Party candidate is differentiated and closer to the "pure" libertarianism than Ron Paul or Dennis Kucinich. However, the gulf between DK and RP isn't as wide as RP supporters would have us believe.
If we can pick-and-choose our libertarian issues in order to determine who the "real" major-party "libertarian" is in this race, then Ron Paul loses points -- particularly with regard to this hypothetical San Francisco gay male voter -- that neither Kucinich nor the actual Libertarian Party nominee would. And these are in areas where Ron Paul is "unlibertarian."
Cheers,
Brian