Elasticsearch is built on top of Apache Lucene and is very similar to technologies like Solr but with a nicer interface (really more like SolrCloud these days).
It is different in that it provides higher level APIs and distributed functionality on top of Lucene. For example, one Elasticsearch index might contain multiple Lucene indices spread across multiple machines, but your application treats it as a single "index".
It is different in that it provides higher level APIs and distributed functionality on top of Lucene. For example, one Elasticsearch index might contain multiple Lucene indices spread across multiple machines, but your application treats it as a single "index".