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The following extra packages will be installed: gdebi-core gir1.2-atk-1.0 gir1.2-freedesktop gir1.2-gdkpixbuf-2.0, gir1.2-gtk-3.0 gir1.2-pango-1.0 gir1.2-vte-2.90 gksu gnome-icon-theme, humanity-icon-theme libcairo-perl libgksu2-0 libglib-perl, libgnome-keyring-common, libgnome-keyring0 libgtk2-perl libgtop2-7, libgtop2-common libpango-perl libvte-2.90-9 libvte-2.90-common<small>The following extra packages will be installed: gdebi-core gir1.2-atk-1.0 gir1.2-freedesktop gir1.2-gdkpixbuf-2.0, gir1.2-gtk-3.0 gir1.2-pango-1.0 gir1.2-vte-2.90 gksu gnome-icon-theme, humanity-icon-theme libcairo-perl libgksu2-0 libglib-perl, libgnome-keyring-common, libgnome-keyring0 libgtk2-perl libgtop2-7, libgtop2-common libpango-perl libvte-2.90-9 libvte-2.90-common</small>The following NEW packages will be installed: gdebi gdebi-core gir1.2-atk-1.0 gir1.2-freedesktop gir1.2-gdkpixbuf-2.0, gir1.2-gtk-3.0 gir1.2-pango-1.0 gir1.2-vte-2.90 gksu gnome-icon-theme, humanity-icon-theme libcairo-perl libgksu2-0 libglib-perl, libgnome-keyring-common libgnome-keyring0 libgtk2-perl libgtop2-7, libgtop2-common libpango-perl libvte-2.90-9 libvte-2.90-common<small>The following NEW packages will be installed: gdebi gdebi-core gir1.2-atk-1.0 gir1.2-freedesktop gir1.2-gdkpixbuf-2.0, gir1.2-gtk-3.0 gir1.2-pango-1.0 gir1.2-vte-2.90 gksu gnome-icon-theme, humanity-icon-theme libcairo-perl libgksu2-0 libglib-perl, libgnome-keyring-common libgnome-keyring0 libgtk2-perl libgtop2-7, libgtop2-common libpango-perl libvte-2.90-9 libvte-2.90-common</small> Basically, using apt-get allows you to pull down packages from a server and install. gdebi allows you to install packages that you have manually or previously downloaded and put on your system.