Do you consider pain perdu and French toast different?

They are very similar and could be the same if crusty French bread is used.

I use homemade brioche for my French toast, and it's very often requested on vacation or visiting friends/family.

Pain Perdu by its title is older crusty french bread that has very limited further use (croutons, casserole binder, etc.) but not good for sandwiches.

The custard I would use is elevated from the quick homemade French toast of my youth, and similar if not the same as pain perdu.

I use Alton Brown's recipe for French toast, it comes out great as written. But I also add vanilla extract and cinnamon.

Alton Brown, French Toast

They are a little different.

Pain Perdu uses thick cut, French bread instead of sliced bread. Also, you soak the bread like you would for a bread pudding. You just dont sqeeze it like for bread pudding. Last, the custard is richer than bread pudding from the cream.

To most, that is all splitting hairs, but there is a slightly differnt technique. French toast can be made on the psot where Pain Perdu needs that extra soak time and thickers sices of bread.