Entity, Entity type, Bundle in d7
Drupal 7 has introduced entity and bundle terminology.
Those objects are more generals that drupal 6 nodes, taxonomy terms, users....
An entity is a something more general that node that has a type that could be "node" "terms" "users", "assets" ...
The equivalent of the content type for d6 nodes are called bundle which is an assemblage of fields on a given entity. So the article node type in d6 would be the entity of type "node" and of bundle "article"