Preferences include settings such as panel positions, measurement options, and display options for graphics and typography. Preference settings specify how InDesign documents and objects behave initially.
Default settings are used for every new document or object you create. For example, you can specify the default font and other type specifications for all new documents or text frames.
Numerous program preferences and default settings are stored in the Adobe InDesign preferences files, called InDesign Defaults and InDesign SavedData. Both of these defaults files are saved each time you exit from InDesign.