Marx's definition of what constitutes a state is so nebulous that you could consider the organizational structure that most libertarians propose to be a state. Not to throw shade at libertarian marxists, of which there are a good handful. His framework of the state and power structures is lacking and not very useful for anarchist analysis and theory. Our conceptions for what a state is and how power functions are very different from authoritarian conceptions. Marxism isn't the end all be all of socialist theory, and if that's as far as you've gone in your study of the topic I'd be happy to provide some anarchist theory and analysis.

I want to write more and get into the weeds of it but I keep tripping over myself wanting to pull all the strings together but there's just too much to break down for a comment. I'm happy to talk more about the differences but I think we may need to narrow the scope a bit more, or take it one thing at a time. Theres like 5 different tangents I could go off on lol. Or I could drop some links if you'd rather have it all laid out in one shot haha