advantage of using spring hibernate over hibernate alone

Spring provides hibernate template and it has many advantages like
1) It removes boiler plate code like getting connection from data source try/catch block for closing connection. So that developer can focus on writing business logic rather then writing boilier plate code every where.

2) Spring hibernateTemplate also throws RunTime exception compared to checkd exception which allows to remove writing try/catch block in each DAO.

3) It also gives richer template class using which developer can write query code easily. This template class also allows to get session explicitly so if developer wants to get session object and work on it then it's possible.

difference between session.flush() and commit() in hibernate

Commit will make the database commit
- Flushing is the process of synchronizing the underlying persistent
store with persistable state held in memory.
ie. it will update or insert into your tables in the running
transaction, but it _may_ not commit those changes (this depends on
your flush mode).

commit can not be rolback