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.
Words nearby which is which
wheyface,
wheyish,
whf,
whf.,
which,
which is which,
which way the wind blows,
whichever,
whichsoever,
whichway,
whicker