Hibernate Search uses Lucene and adds some sugar on it.
Some advantages of Hibernate Search over raw Lucene:
- changes in your database (made by Hibernate Core) are propagated transparently for you to the Lucene index
- indexing is optimized for you. HSearch does for Lucene that Hibernate Core does for
JDBC - queries return managed objects instead of the Lucene Document (which is basically a hashMap of Strings
- clustering out of the box