travel from Paris to Bordeauxp

Traveling by TGV is faster and less expensive than flying. There are numerous trains throughout the day and the trip from Montparnasse is just over two hours. Take advantage of discount train fares if you can purchase early enough.

https://www.raileurope.com/index.html

Steve, are you really recommending RailEurope, that well-known reseller in North America?
Surely you mean: https://www.trainline.eu/ which is a French based company offering the same trains and prices as SNCF, which has a less than easy-to-use website.

Either web site works fine. Prices are not exactly the same but similar - e.g., $55 from Rail Europe or €42 from TrainLine for an advance discount on the same train on a test date of October 10. Rail Europe's exchange conversion will vary over time but is not changed daily. If your credit card charges an annoying foreign transaction fee, then that eats up any price difference.

Now that the TGV trip has been cut to 2 hours, there's no reason to go any way other than the train. Driving takes 6 hours, and who knows how long the plane would take when you figure in getting to and from the airport and security.