which is which

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.

Common Names:

Name	Pronounced	Usage
Rosy	ROZ-ee	English
Peer	-	Danish, Norwegian, Swedish
Tara (2)	-	Hinduism, Indian, Hindi, Nepali
Vickie	['viki]
Ivah	-	Biblical
Tuukka	-	Finnish