which is which

Idioms  

1. What particular one is what particular one, or what is the difference between different ones. For example, These twins look so much alike I can't tell which is which, or Both our raincoats are tan; do you know which is which? This idiom was first recorded about 1412.

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Example Sentences

See Examples For:

which is which

"You've got to do your research and really study and master the craft of telling which is which, as it's such a big problem now," said Jacob, who runs Knight Vintage in Cardiff.

From BBC ● Apr. 12, 2025

And how does Google Maps determine which is which?

From Slate ● Oct. 26, 2023

Fact, fiction and conspiracy blur together until you can’t tell which is which, and you almost cease to care.

From Los Angeles Times ● Sep. 8, 2023

Maali has to figure out which is which, as he struggles to solve the mystery of his own death.

From Washington Post ● Nov. 1, 2022

The writer should refer to each theme in a consistent way, one that allows the reader to know which is which.

From "The Sense of Style" by Steven Pinker