Eli5: Some ice cream recipes put ice + salt outside the recipient to make it cool faster. But in the winter, salt is put on snow on the street to melt faster. Why one make cool and other melt?

Question

Edit: thank you all for the explanations, I now have understood much more!

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Answer 1

I’m no expert, but I believe salt makes the freezing point lower, this allows the water the fills the whitespace in between the ice cubes to be colder. The water is more efficient at changing the temperature of the internal wall of the ice cream container in the middle because it presses up against it and the ice over a wide area, where the ice cubes only touch the inner wall at points.