yes, the upgrade package only upgrades the core itself, some people did not like the fact that performing a portal upgrade upgraded all the modules also (particularly as the look and feel of some of them change substantially). If you want to perform module installs as well, download the install package, it contains the latest version of the modules at the point the package was assembled. If you don't want some of the modules to install, just remove them from the Install\Module folder before you update.

Cathal