A Couchbase strength is its support for a wide range of flexible operations. Query with SQL++, a full SQL implementation for JSON or key-value lookups, which do not require the creation of any additional indexes and will read data directly from the built-in managed cache. Further, Couchbase includes multi-dimensional scaling of its services including: Full-Text Search, Analytics, and Eventing.
CouchDB functions as a pure document store. As a result, developers often find the database system is difficult to query. Data can be retrieved through a system of views, which can be cumbersome and limited. Also, there is a lack of a subdocument API, which means you can only read and write a full document using its key, which can affect performance on large documents.