Whats the difference between frame and widget containers?

[n34rt]

I'm referring to these:

Also if possible whats dock widget used for?

[jsulm]

@n34rt QFrame is a subclass of QWidget and can be used if you need a frame (lines) around the widget, see https://doc.qt.io/qt-6/qframe.html
Dock widget: it's also explained in documentation https://doc.qt.io/qt-6/qdockwidget.html