Apples and oranges~From Human: The Science Behind What Makes Us Unique by Michael S. Gazzaniga, pages 250-251:
Harvard researchers Alfonso Caramazza and Jennifer Shelton claim that there are domain-specific knowledge systems for animate and inanimate categories that have distinct neural mechanisms. Indeed, there are patients with brain damage who are very poor at recognizing animals but not man-made artifacts, and vice versa. If you have a lesion in one spot, you can't tell a tiger from an Airedale, and if it is in another spot, the telephone becomes mysterious object. There are even people with brain lesions that make them specifically unable to recognize fruit.
For such people, the expression "apples and oranges" means nothing!
Interesting stuff... and weird...