https://www.cato-unbound.org/2009/04/13/peter-thiel/education-libertarian
What is up with this?
Best I can tell, Libertarianism is a kind of an explanation of why there are poor people, and how not to feel bad about it. I may be wrong!
Libertarianism generally supports the idea of minimal government intervention in people's lives. This means both avoiding restrictions on what people are allowed to do (e.g. legalize drugs, oppose religiously-driven laws that restrict the freedom of gay and trans people), and also avoiding governmental efforts to actively assist people (e.g. no social security or Medicare). Most libertarians would like to see a small, weak government that just does the minimum required to ensure that one person's freedom isn't impinging on another person's freedom. They typically oppose military intervention - many oppose the idea of a standing military at all - and generally advocate for open boarders.
Fascism on the other hand generally advocates for a very strong government that aggressiveky restricts individual freedom in the hope of achieving the goal of social and cultural stasis, or national military power. Fascists typically believe that individuals should submit to the will of the state (e.g. dramatically limiting free speech, banning "deviant" lifestyles). They tend to support aggressive military actions and closed borders.
Libertarians believe personal freedom is an end in itself. Fascists seek security and safety for their immediate society and tend to not care much about personal freedom. Whereas libertarians tend to value every individual, fascists would argue that any given set of individuals should be sacrificed if it benefits the state.
As with any political identity though, there are a wide range of beliefs - and people - who have been identified with these two labels. So, YMMV.
In a libertarian society, free individuals could still build walls around the borders of their properties and hire armed guard to shoot at anybody not of their colors trying to cross it.
In a fascist society, the bosses could still force the people to accept submerging immigration from another continent, and brainwash the indigenous people to abort and use contraceptives, so that it is eventually exterminated.
ie. Libertarianism, Fascism, Communism, Capitalism, Republic, Monarchy, etc, don't matter much, to the persons who have the power to decide the policy and goals. The question is who decides, and what policy and goals they decide.
Your question is what's the difference between a Libertarian and a Fascist. I've asked self identifying Libertarians what is the difference between a Libertarian and a conservative and what I got was a complaint about liberals. They occasionally have a wacky opinion like being for drug legalization and very occasionally being anti death penalty. But really, I can't tell them apart from garden variety conservatives.
A buddy of mine is an Ayn Rand reading Ronulan. Birther. Dude, you're not a Libertarian. You're a Fakebertarian.