ejabberd vs Sparrow: What are the differences?

Developers describe ejabberd as "A scalable and robust instant messaging server". It is a distributed, fault-tolerant technology that allows the creation of large-scale instant messaging applications. The server can reliably support thousands of simultaneous users on a single node and has been designed to provide exceptional standards of fault tolerance. On the other hand, Sparrow is detailed as "A really fast lightweight queue written in Ruby that speaks memcache". Sparrow keeps messages in memory, but persists them to disk, using Sqlite, when the queue is shutdown.

ejabberd and Sparrow belong to "Message Queue" category of the tech stack.

ejabberd is an open source tool with 4.18K GitHub stars and 1.25K GitHub forks. Here's a link to ejabberd's open source repository on GitHub.