A package can have one of the following statuses:

available

The package is not installed, but can be downloaded and installed from the package archive.

avail-obso

The package is available for installation, but a newer version is also available. Packages with this status are hidden by default.

built-in

The package is included in Emacs by default. It cannot be deleted through the package menu, and by default is not considered for upgrading (but you can change that by customizing package-install-upgrade-built-in, Package Installation).

dependency

The package was installed automatically to satisfy a dependency of another package.

disabled

The package has been disabled using the package-load-list variable.

external

The package is not built-in and not from the directory specified by package-user-dir (Package Files). External packages are treated much like built-in packages and cannot be deleted.

held

The package is held, Package Installation.

incompat

The package cannot be installed for some reason, for example because it depends on uninstallable packages.

installed

The package is installed.

new

Equivalent to available, except that the package became newly available on the package archive after your last invocation of M-x list-packages.

obsolete

The package is an outdated installed version; in addition to this version of the package, a newer version is also installed. @c unsigned (installed, but not signed; Package Signing),