Zend Studio je PDT rozsirene o Subversion, refactoring, unit testing, tunneling + (S)FTP, dva druhy profilerov, kod analyzer, JDBC driver a integraciu so Zend Framework, Zend Platform. a Zend Guard. Su to v podstate veci, ktore ti zvysuju produktivitu, ale nie az tak kriticky, aby si nutne musel kupovat Zend Studio. :)