That’s not really correct. Standalone is fine for production. It’s commonly used in production, especially when you only need one instance of the server.
Domain is used when you run several instances of JBoss AS and you want a single point where you can control configuration from. You can read more about it in the documentation.
The link has been changed to the latest version of WildFly as the JBoss AS 7 documentation has been archived, but is still available at https://docs.jboss.org/author/display/AS71/Admin%20Guide.html#8094211_AdminGuide-StandaloneServer