[CentOS] postfix-2.2.10-1.1.el4.centos.mysql_pgsql.base.i386.rpm vs postfix-2.2.10-1.1.el4.centos.mysql_pgsql.plus.i386.rpm

Hi,
what are the differences between
postfix-2.2.10-1.1.el4.centos.mysql_pgsql.base.i386.rpm vs
postfix-2.2.10-1.1.el4.centos.mysql_pgsql.plus.i386.rpm. Changelogs are
the very same and there's no announcement.
Thanks,
David Hrbáč