Yes, you will need a visa to enter France and travel between the airports. What’s more, an airport transit visa (type A) will not do; rather you need a short-stay visa (type C) – if the application form asks about your travel purpose, you select transit.
On another note, travel between the airports is very convenient. For 21 euros, you can book a direct shuttle bus (line 3), which runs every 20 minutes and takes 75 minutes between the airports
The only way to get from one of these airports to the other is to enter France and take ground transportation. (You can’t even transfer between international flights between the two terminals at Orly without entering France).
In order to enter France as an Indian citizen you need a Schengen short-stay visa. This must be applied for in advance from the French embassy/consulate in your country of residence.
Credit:stackoverflow.com‘