In eZ Platform, you find 3 search engines possibilities :
Legacy, a Database based search with baseline capabilities
Status colour Yellow title >= 5.4.5
Status colour Red title Experimental
The Search Engines integrations have real search capacities and are not just filtering the results.
In the last version, ElasticSearch is more advanced than Solr : it has Field Filters, Field Sort Clause, Language AnalysisAs of
eZ Publish Platform 5.4.5 and higher, Solr is the recommended search engine for production use. Solr provides the most most advance search capabilities, and system performance. Currently Elastic Search is experimental, and not professionally supported.