Differences Between Elasticsearch and OpenSearch

CSS provides a fully managed cloud search service based on open-source engines. CSS Elasticsearch and OpenSearch both have the following core capabilities:

Unified architecture: a distributed, RESTful search engine, supporting near-real-time search and analytics over petabytes of data
A wide range of use cases: log analytics, enterprise search, big data analytics, vector search, semantic search, RAG, etc.
Enhanced features: deep optimization based on open-source versions, high performance, high availability, cost effective, and fully managed

A Comparison of Core Functions

**Table 1** A comparison of core functions between Elasticsearch and OpenSearch
Dimension	CSS Elasticsearch	CSS OpenSearch
Origin	Built on Apache Lucene, Elasticsearch is a mature, widely adopted search engine.	OpenSearch, a fork of Elasticsearch, inherits its core search and analytics capabilities while keeps evolving.
Compatibility	Compatible with the Elasticsearch ecosystem Compatible with later-version Elasticsearch SDKs	Compatible with the OpenSearch ecosystem Compatible with Elasticsearch 7.10.2
Version policy	The mainstream version is 7.10.2, which will be continuously optimized. We recommend upgrading all Elasticsearch clusters to this version.	The version will be continuously updated to keep up with open-source innovations.
Kernel features	CSS will provide continuous kernel enhancement.	CSS will integrate its own unique capabilities with open-source innovations to ensure continuous kernel enhancement.
Evolution	Emphasizes the stability of the 7.x version and enhancements.	Actively integrates new cloud native features.

Engine Selection Suggestions

**Table 2** When to choose Elasticsearch or OpenSearch
Scenario	Recommended Engine	Reason
Running Elasticsearch 7.10.2 or earlier for long-term stability	Elasticsearch	Mature and stable, fully compatible with the native Elasticsearch toolchain Compatible with later-version Elasticsearch SDKs Backed by the unique strengths of CSS (such as vector search)
New features of Elasticsearch 8+ are required	OpenSearch	Inherits Elasticsearch capabilities while keeps evolving Backed by the unique strengths of CSS (such as vector search)
Smooth migration of existing Elasticsearch 7.x clusters	Elasticsearch or OpenSearch	Both are compatible with Elasticsearch 7.10.2 APIs, with a similar migration cost.

Parent topic: Product Overview