which is which

Idioms

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.

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

"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

The best way to tell the difference between the two is to really look closely at the bodies to identify which is which, rather than solely choosing based on a fishmonger's label.

From Salon • Jun. 6, 2022

See if you can tell which is which by looking at my diagram.

From "Flying to the Moon: An Astronaut's Story" by Michael Collins

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023