CloudSearch

Amazon CloudSearch is a fully managed service in the cloud that makes it easy to set up, manage, and scale a search solution for your website.
It enables you to search extensive collections of data such as web pages, document files, forum posts, or product information.
Add search capabilities to your website without becoming a search expert or worrying about hardware provisioning, setup, and maintenance.

OpenSearch (ElasticSearch)

It is a managed service that makes it easy to deploy, operate, and scale OpenSearch, a popular open-source search and analytics engine.
OpenSearch Service offers security options, high availability, data durability, and direct access to the OpenSearch API.