New features in Cloud Search Service:

• Tags can be in dot format and can contain a maximum of 64 characters.
• Enhanced CSS aggregation capability
• CSS interconnects with ELBv3 and can be bound to ELBv3 across tenants
• Elasticsearch supports zstd compression
• Replacement of specific nodes
• Ability to change node flavors
• Ability to scale individual nodes
• Option to migrate to a different AZ
• Ability to change security mode on already existing cluster
• Option to add master/client nodes on already existing cluster

New features in Opensearch Service:

• Opensearch supports the storage and compute separation plug-in
• Set the Opensearch cluster as an independent Opensearch engine, which is not a version of ES
• The import performance of Opensearch is enhanced

See Cloud Search Service section for more information in our Help Center.