'apt upgrade' doet iets anders dan 'apt-get upgrade'

[Cecil Westerhof <Cecil@decebal.nl>]

Wanneer ik 'apt upgrade' doe, dan krijg ik:
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    Calculating upgrade... Done
    The following NEW packages will be installed:
      cups-pk-helper gir1.2-atk-1.0 gir1.2-gdkpixbuf-2.0 gir1.2-gtk-3.0 gir1.2-notify-0.7 gir1.2-packagekitglib-1.0 gir1.2-pango-1.0
      gir1.2-polkit-1.0 gir1.2-secret-1 libappstream4 libpackagekit-glib2-18 libpangoxft-1.0-0 libstemmer0d packagekit packagekit-tools
      python3-cairo python3-certifi python3-chardet python3-cups python3-cupshelpers python3-idna python3-requests python3-smbc
      python3-urllib3 system-config-printer system-config-printer-common system-config-printer-udev
    The following packages will be upgraded:
      chromium chromium-common chromium-driver chromium-l10n chromium-sandbox chromium-shell
    6 upgraded, 27 newly installed, 0 to remove and 0 not upgraded.
    Need to get 106 MB of archives.
    After this operation, 38.4 MB of additional disk space will be used.
    Do you want to continue? [Y/n]

Terwijl wanneer ik 'apt-get upgrade' doe ik krijg:
    Reading package lists... Done
    Building dependency tree
    Reading state information... Done
    Calculating upgrade... Done
    The following packages have been kept back:
      chromium chromium-common chromium-driver chromium-l10n chromium-sandbox chromium-shell
    0 upgraded, 0 newly installed, 0 to remove and 6 not upgraded.

Ik weet het niet 100% zeker, maar volgens mij gebeurd dit pas sinds
kort. Er staat me bij dat apt van de week is geupdated.

Wat is hier aan de hand en is er wat tegen te doen?

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof