JBoss Tools is a set of plugins for Eclipse.
JBoss Developer Studio = Eclipse + JBoss Tools
If you didn't work with Eclipse before I would recommend you to install JBoss Developer Tools instead of installing Eclipse + JBoss Tools manually.
And BTW if you still want to use Eclipse Juno + JBoss Tools, be aware that JBoss Tools 3.3.0 supports Eclipse Indigo. You can install it on Eclipse Juno, but we don't guarantee that everything will work.
See https://community.jboss.org/en/tools/blog/2012/06/21/jboss-tools-33-and-developer-studio-50-final-release