Assimp also uses bones. (aiBone structure)
Add "node" to the list of synonyms. Assimp uses the term node.
I remember struggling with assimp too initially.
It's been a few months since I last touched animations but aiBones only hold information such as inverse bind pose matrix but they call it offset matrix, bone indices & weights. The hierarchy is not represented at all here. That's where the aiNodes intervene. You have to construct a tree and match corresponding aiBones to aiNodes, using the names.