Can somebody explain to me the difference between a content type and a bundle? Is the latter just a bundle for the entity node?
Bundle is a generic term that applies to every entity Drupal or third-party modules define; content type is a specific term that applies to nodes.
Since nodes and content types were introduced a way before Drupal 7, content type was the first concept introduced, which then got expanded into the bundle concept when entities were introduced in Drupal 7.
So, yes, a content type is a bundle for the Node entity.