"Why do you keep saying that " he asked in response "Apples and oranges aren't that different really. I mean they're both fruit. Their weight is extremely similar. They both contain acidic elements. They're both roughly spherical. They serve the same social purpose. With the possible exception of a tangerine I can't think of anything more similar to an orange than an apple. If I was having lunch with a man who was eating an apple and-while I was looking away-he replaced that apple with an orange I doubt I'd even notice. So how is this a metaphor for difference I could understand if you said 'That's like comparing apples and uranium ' or 'That's like comparing apples with baby wolverines ' or 'That's like comparing apples with the early work of Raymond Carver ' or 'That's like comparing apples with hermaphroditic ground sloths.' Those would all be valid examples of profound disparity."