Hello!
I'm french and studying atpl theory in france.
What I know is the atpl theory course lasts 12 month in France and 6 month in Belgium, spain... I don't really know the reason...and I wonder how the people in theses countries do that ! 6 month! it is very short!
anyway, I have looked a book of Oxford, and jeppesen, and I can say that we are more mathematics to learn! but sometimes it's very dificult and not necessary.