There are some similarities between the two; they both support JMS 1.1 and run inside JBoss 4.x.

However ActiveMQ does offer some specific differences and advantages (at least from our perspective)

• ActiveMQ works great in any JVM not just inside the JBoss application server
• ActiveMQ comes complete with a large number of Cross Language Clients
• ActiveMQ supports many different Protocols such as Ajax, REST, Stomp, OpenWire, XMPP
• ActiveMQ supports a large number of advanced features like Message Groups, Exclusive Consumer, Composite Destinations, Advisory Message support
• ActiveMQ supports reliable connections with configurable automatic reconnection
• ActiveMQ has great Spring Support
• ActiveMQ supports distributed destinations across networks
• ActiveMQ is very fast; often 10x faster than JBossMQ.

Performance guides

There is a FuseSource tuning guide

If you're not convinced by performance reports then please do try running performance tests yourselfs. You might wanna check out our overview of Performance or try using out the ActiveMQ Performance Module Users Manual

More on JBoss Integration

Integrating Apache ActiveMQ with JBoss