JBoss 4.x and JBoss 7 are many years apart. Listing features available etc would not really be feasible, you can be pretty sure everything has changed from classloading to logging. Any reason you're not moving to WildFly 8? In terms of pre-requisites for AS 7, you can find everything you need to know about setting up in the documentation. Getting Started Guide - JBoss AS 7.2 - Project Documentation Editor - The first thing you will see here is the table of the EE 6 technologies in this release. I'm not sure JBoss 4.x was even EE certified.
Thanks for your response, can you tell me what are the difference between AS 7 and 8. Also let me know if there is any license and support cost for AS 7 and 8.