Apples and oranges binomial
Used to refer to two objects or people that are very different
Although they are brothers, they are like apples and oranges.
These restaurants are apples and oranges, so we cannot compare them.
To be totally different from something.
The idea of this metaphor came from the difference of apples and oysters, which was first recorded in John Ray's proverb collection of 1670.
If someone has a cast iron stomach, they have a strong stomach that can digest unusual food and even bad food without being ill.
Jimmy must have a cast-iron stomach, when he drank milk with lime juice and felt perfectly fine afterward.