Let me guess - somewhere embedded in the platform, the LP supports child porn, open borders, and unlimited drug usage, right? Ergo, they're liberals?
The L party is nothing but a straw man useful when conservatives want to bash libertarian principles.
Less government pretty much sums up 90% of the platform. What is left? So is your question pretty much "Other than 90% of the platform, how do Libertarians differ from liberals?"
You just dismiss out of hand planks on the platform like elimination of welfare, elimination of antitrust laws, free trade markets, deregulation of markets, privatization of government industry, etc. Yeah, other than 90% of their beliefs, they are just like liberals.