Both of these terms have more than one meaning, some of which overlap with each other, so the question is impossible to answer objectively. Both terms can refer to a belief system that people would usually describe as “left-wing” (~ “anarchism”, “libertarian socialism”, “left-libertarianism”, “anarcho-communism”), or one that people would usually describe as “right-wing” (~ “anarcho-capitalism”, “(right-)libertarianism”, “minarchism”).

Myself, I use “libertarian” as the antonym of “authoritarian”, so “libertarian” is a positive term for me; after all (like most people) I think authoritarianism is a bad thing. But libertarianism doesn’t need to be, nor is it usually, completely 100% against all hierarchy and all authority. It can still hold that some hierarchy and authority is necessary for getting things to function, but that it should be limited or accountable.

I don’t consider myself any sort of “anarchist”, I think it’s impossible to completely do away with authority, hierarchy, or government, no matter how much I think those things should have limits to their powers.

Of course I also very strongly believe that what leftists call “capitalism” (i.e. the economic system the world currently mostly runs on) is not, like they say, just another class society where the function of the state is to keep the ruling class in power. There are no formally defined classes in a liberal democracy like there were under feudalism. The mere existence of private property rights and wage labor doesn’t create a class society; those things have existed for millennia of human history and are here to stay. So for that reason I disagree with anarcho-communists when they say that in an “anarchy”, there would no longer be private property.