I'd recommend you check out those books because they explain it far better than I or anyone else could hope to in a single comment, but it essentially comes down to the capitalist/worker divide. The capitalist will always be on top, and the worker will always be subservient to their interests. That is how it is hierarchical, because there will always be the capitalist class imposing it's will on the working class, and so anarchists and communists hope to abolish the class system. However the two groups disagree massively on how to achieve that abolition.

Capitalism is more about a few controlling the means of production than it is about market activity. People tend to think of it as a market economy but it's really about who has power and reaps it's rewards.

Actually what you're describing is just the fact that the word "capitalism" is used to mean markedly different things by different groups of people, which makes it a bad word to use in discussions between people with different perspectives.

Karl Marx's definition of "capitalism" is very different from Ayn Rand's definition of "capitalism". And both of them are very different from the "capitalism" that describes the economy as it actually exists in the present day.