I'm not sure whether my math at HS was good or during my higher edu it was shitty, but what do you actually mean by "think in a new way"? I don't see big diffe

I'm not sure whether my math at HS was good or during my higher edu it was shitty, but what do you actually mean by "think in a new way"? I don't see big difference between e.g math analysis in college and advanced math in HS. Except ofc complexity of concepts and tricks used there. Only graph theory looks relatively different to that.