[OK]

The [OK] button executes the [Apply] button to accept your changes and then closes the Dialog.

[Process]

The [Process] button is used to perform the operation of a command dialog. It executes the command associated with the settings in the dialog. Dialogs using this button are mostly in the Process menu.

[Apply]

This button accepts the changes you have made in the dialog. After clicking [Apply] you can continue working in the dialog.

When [Apply] is located with [Process] and [Close] on a command dialog, it accepts your settings but does not operate the command.

[Cancel]

[Close]

These buttons close the dialog window without updating your changes since the last time you clicked [Apply].

[Default]

This button appears in some property dialogs. It saves the dialog settings as default values for all future cases. In comparison, the [Apply] button saves the settings only to the current view window that was open when this dialog was opened.