Re: Pi vs Mac Mini
I think the comparison operates on the structure that apples and oranges are similar enough that you can compare them in a broad sense, but doing so on specifics is focusing on the wrong thing. Therefore:
"This yellow apple is not as crunchy as that red one, so I like it less." is fine.
"This orange from California is sweeter than that one from Florida, so I like it more." is fine.
"I tried the apples at the supermarket, but they seem old so I ate oranges." is fine.
"This apple had a thinner skin than that orange, so I like it more." is missing the point because oranges have rinds and apples don't (well functionally they don't). Meanwhile, using a general comparison such as "Oranges have thick rinds and apples don't, so I prefer apples." is fine.
Thus, comparisons like "Raspberry pi boards are cheaper and easier to modify than mac minis", "The cost of the raspberry pi is commensurate with its components, but the mac mini is hideously overpriced", and "The raspberry pi has a GPIO interface, but the mac mini does not" are all completely valid comparisons. Statements like "Both of the machines have 1.4ghz processors, but the mac mini is more expensive" are missing the point because the processors are different and so the comparison can't be used to correctly differentiate between the two.