To add what @antisocialist posted, the best way to think about it is the totality of things.
When you look at Web2, the database is located on different servers. This is no different from Hive. However, under that premise, one company controls all the servers. Hence, whatever is on Facebook is owned by that company.
Hive nodes are run by different, unrelated people. They are spread throughout the world and are free to run it in any infrastructure they want. While some will use one company, others will opt for something different.
Keep in mind, this only applies to text. That is what is on the blockchain. Images are centralized since that is run through one or two image servers controlled by the providers (like Blocktrades).