Context menu—Typically triggered by a right-click,
a context menu is positioned close to the mouse,
and is dismissed by clicking anywhere,
selecting an option from the menu, or clicking outside it.

Tooltip—Typically triggered by hovering for
200-400ms over an interactive element,
a tooltip is usually anchored to a widget
(as opposed to the mouse position) and is dismissed
when the mouse cursor leaves that widget.

Popup panel (also known as flyout)—Similar to a tooltip,
a popup panel is usually anchored to a widget.
The main difference is that panels are most often
shown on a tap event, and they usually don’t hide
themselves when the cursor leaves.
Instead, panels are typically dismissed by clicking
outside the panel or by pressing a Close or Submit button.

To show basic tooltips in Flutter,
use the built-in Tooltip widget: