Datomic vs RethinkDB: What are the differences?

Developers describe Datomic as "The fully transactional, cloud-ready, distributed database". Build flexible, distributed systems that can leverage the entire history of your critical data, not just the most current state. Build them on your existing infrastructure or jump straight to the cloud. On the other hand, RethinkDB is detailed as "JSON. Scales to multiple machines with very little effort. Open source". RethinkDB is built to store JSON documents, and scale to multiple machines with very little effort. It has a pleasant query language that supports really useful queries like table joins and group by, and is easy to setup and learn.

Datomic and RethinkDB can be categorized as "Databases" tools.

RethinkDB is an open source tool with 22.4K GitHub stars and 1.74K GitHub forks. Here's a link to RethinkDB's open source repository on GitHub.

miDrive, Rove.me, and Lastbackend are some of the popular companies that use RethinkDB, whereas Datomic is used by Rareburg, Exicon, and Yieldbot. RethinkDB has a broader approval, being mentioned in 37 company stacks & 25 developers stacks; compared to Datomic, which is listed in 7 company stacks and 5 developer stacks.