Assigning an application is very straightforward, as it basically just installs the software on the next log in after the GPO is applied. Publishing a package however is a different thing all together. When you publish a package, it is not actually installed on the computer, but rather, it gives the end user the option of installing it. Once it is applied to a specific computer, the end user of that computer can open the Add/Remove Programs dialog from the control panel and choose to install the package from there.
It is also important to note that a package can be assigned to a user or computer, but can only be published to users.
Chris Sanders is the network administrator for one of the largest public school systems in the state of Kentucky. Chris's specialties include general network administration, windows server 2003, wireless networking, and security. You can view Chris' personal website at www.chrissanders.org.