Difference between QPushButton and QToolButton

QToolButton is part of a group of widgets in the QtWidgets module that is focused around QAction: QMenu, QToolBar, and so forth. QPushButton is just a button. As a result, QToolButton is much more complex under the hood than QPushButton. A (not complete) list of examples:

• QToolButton is designed to be tightly integrated with QAction. Changing the icon, text, etc. of a tool button's default action is reflected on the button.
• You can change the layout of the tool button contents (icon only, text only, text beside icon, text below icon).
• QToolButton supports a "split" button type where a sidebar hot zone opens a menu instead of triggering the default action.
• Tool buttons can be created directly in a QToolBar by adding an action, while other widgets must be explicitly added.

Also note that:

• QToolButton has smaller default internal margins than QPushButton, reflecting that it is meant to be displayed in a tight row or grid. QPushButton is more for "Ok"/"Close" type buttons that contain text with an optional icon.
• A QToolButton should generally have an icon. A QPushButton should always have text.

From Qt doc: http://doc.qt.io/qt-5/qtoolbutton.html#details

"A tool button is a special button that provides quick-access to specific commands or options. As opposed to a normal command button, a tool button usually doesn't show a text label, but shows an icon instead."

When i want a button in the GUI simple with only an icon, I use QToolButton. But when i want a classic button, i use QPushButton.

No big differences,