User assistance system for vehicle

A portable information terminal stores first function list information indicating the contents of functions installed on a first vehicle. When a user carrying the terminal gets in a second vehicle before driving, the second vehicle acquires the first function list information from the terminal. The second vehicle compares the acquired first function list information with second function list information indicating the contents of functions installed on the second vehicle. The second vehicle acquires a functional difference between itself and the first vehicle and notifies the user of the difference.