Orly to Charles de Gaulle  
Bus:
Air France provides bus service between the two airports. (Anyone can take this, regardless of which airline company you are flying). It costs approximately 16 euros for a one way ticket.
Taxi:
Taxi fares depend on traffic, therefore they can be rather expensive. In addition to the metered fare, there is a supplement for each piece of luggage, as well as for a fourth passenger. It is your responsibility to have the correct amount of money (in Euros) for the fare and it is customary to tip the driver about 10% of the fare.
All information is subject to change. Please contact the individual ground transportation companies directly to confirm all schedules and pricing.