Hibernate Session vs. EntityManager

The answer to the question below is depressingly easy. I was overthinking the problem. Session is Hibernate's custom implementation; EntityManager is the standard JPA creature. If you want to stick to the standards (in this case, I do, although the odds of our shifting to a different JPA provider are very slender), stick to EntityManager. The big thing I'm missing out on so far is access to Hibernate's various CascadeTypes; the JPA default CascadeTypes are rather limited.