dpkg-query vs apt-cache [duplicate]

I noticed an interesting phenomenon and I am looking for an explanation. On my Ubuntu system, dpkg-query cannot find some uninstalled packages which apt-cache can find. For instance,

dpkg-query -l libssl-dev

gives me:

dpkg-query: no packages found matching libssl-dev

while:

apt-cache show libssl-dev

finds the package information. At the same time, dpkg-query can locate other uninstalled packages, e.g. gimp and show their status as uninstalled. Why are some packages not visible to dpkg-query?

Basically, dpkg-query shows you what is installed on your system, or even packages which has been installed on your system and then been removed at some point.

Interestingly enough, if a package uses a dependency of another package, dpkg may list them as installed even though one of them was never fully installed on the system.

But apt is used to download packages from the repositories defined in your sources.list and sources.d/* directory.

in other words, apt-cache shows the packages that "could be installed" on your system not the ones already installed/uninstalled.