What is the difference between Lucene and Elasticsearch

Question

I know ElasticSearch is built upon Apache Lucene but I want to know the significant differences between the two.

Answer 1

I'll answer from a usage perspective.

Lucene is a search engine library. You'd want to use it to build your own search engine: either a new Elasticsearch or Solr competitor or something narrow for your use-case (e.g. text analysis).

Elasticsearch is a search engine. Most people use it for log aggregation, product search, or a variant of these two (e.g. social media analysis or finding relevant people for some search criteria). It's built on top of Lucene, so it exposes most (though not all) of its features. It also adds a lot on top, most significantly:

• REST API
• query DSL
• distributed system (sharding, replication, cluster management)
• facets/aggregations
• additional features for common usage (e.g. ingest processing) and management (APIs for monitoring its relevant metrics, backup and restore, etc)