Amazon MemoryDB vs. Amazon ElastiCache

Amazon MemoryDB for Redis is a Redis-compatible, durable, in-memory database that delivers ultra-fast performance and Multi-AZ durability. With Amazon MemoryDB for Redis, you only pay for what you use with no minimum fee. A node is the smallest building block of a MemoryDB cluster. Each node supports varying amounts of computation and memory capacity, and you can select a node type based on your needs. You are charged based on three components: on-demand instance hours per node, volume of data written to your cluster, and snapshot storage that you use.

Amazon ElastiCache is a fully managed service that makes it easy to deploy, operate, and scale an in-memory data store and cache in the cloud. Often working in conjunction with other AWS database and storage services, ElastiCache ensures modern applications meet real-time requirements for high data throughput and sub-milli second response times, while serving millions of simultaneous requests. Amazon ElastiCache supports two open-source in-memory engines: o Redis - a fast, open source, in-memory data store and cache.