This document provides an overview and comparison of key-value stores and document databases. It discusses that while they are conceptually similar in storing and accessing data via keys or queries, key-value stores treat aggregates as opaque while document databases are aware of data structures. Sample use cases are given for each: key-value stores for session data and shopping carts, document databases for content management and analytics where structure is important. The document concludes that the right database depends on the job and tradeoffs.