Dammit, Mlle, we are nerds. We are nerds on the internet. If we don't have this argument, then who the hell will? Those damned LARPers down at the Chortling Goblin? I don't think so.
PHH, humans have been cultivating both apples and oranges for longer than there has been an English language. I daresay that most of those differences were pretty well known before the phrase was grown. Sure, they didn't know about things like genetics, but they did know that apples grew well one way, oranges another. They knew that the ways you harvested the one didn't apply to the other. And you don't eat the two the same. You almost always peel an orange, and then eat the easily-separable pieces. Peeling an orange amounts to pulling the skin away. Apples typically aren't peeled when eaten plain, and if they are, it involves a knife.
And no shit they're less different than, say, apples and steak or oranges and radioactive waste. That's the point. They're something that is similar enough that someone might compare it. No one's gonna compare an apple to a cow. But at the same time, you can't fault an apple for not being a good orange. You can't fault an orange for not having a nice smooth green skin. That's why this is a vital issue to the American People in these troubled times.