You might want to check out
As you said,
apt-get update fetches the list of packages from the repository. To update your system, you would then normally follow it with
In order to have
apt-get only show you what it would otherwise do, you can add the
-s switch. Thus, to show what updates are currently available, issue the following:
apt-get -s upgrade
Another possibility, according to the man page (It's been a few years since i ran anything Debianish), is
apt-get --show-upgraded update (or possibly
apt-get --show-upgraded upgrade) which apparently will
Show upgraded packages. Print out a list of all packages that are to be upgraded.
Haven't tried that (I think), but probably does what you want.
Rather than updating the entire system, I would like to get a list of updates and then select the updates I would like to install. I know that running the command apt-get -s upgrade does a dry run but what I would really like is to compare what I have installed and what I would like to update akin to Windows Update
It sounds like what you want is a package manager with an interactive interface. I once liked
aptitude, it has a neat ncurses interface and lets you select the packages you want to update from a list of upgradable ones.
If you rally are into stuff modeled on Windows Update, I believe Synaptic (and all the other "different" package manager GUIs sprung out from Ubuntu) has "nice" checkboxes next to package names for things you want to upgrade.