A fellow blogger and far better writer, Silverfiddle at Western Hero has written an awesome layman's outline of Libertarianism.
Libertarians and conservatives are two different animals. If you need an in-depth explanation, just try calling a libertarian a conservative on steroids or some such, and you will be treated to a full, vociferous explanation.
Conservatives want to conserve; libertarians, as the name implies, put personal liberty first. From there, libertarianism branches out into a multitude of variants.