Isn't saying "Pluto and Charon are totally different" the same as saying "Earth and its Moon are totally different"?
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Thank you for this explanation. Very clear and made the difference more reasonable :)
I think what they mean is that Pluto and Charon could have very different compositions, while the Earth and the Moon are nearly the same composition.
Many people saying Pluto is not a planet, and the two might orbit around each other.