区別(くべつ)をつけるto distinguish between, to tell the difference between

子供(こども)は善悪(ぜんあく)の区別(くべつ)をつけられません。

Children cannot distinguish between good and evil.

社長(しゃちょう)：「仕事(しごと)中(ちゅう)は公私(こうし)の区別(くべつ)をつけるべきだよ。」

President: "You should distinguish between public and private matters during work."

寝起(ねお)きで夢(ゆめ)と現実(げんじつ)の区別(くべつ)をつけられませんでした。

Upon waking up, I couldn't distinguish between dream and reality.

男女(だんじょ)の区別(くべつ)をつけるのは良(よ)いが男女(だんじょ)で差別(さべつ)するのはいけない。

It's good to distinguish between men and women, but it's wrong to discriminate against them.

公私(こうし)の区別(くべつ)をつけられないような彼(かれ)が部長(ぶちょう)になることはないでしょう。

It is unlikely that someone like him, who cannot distinguish between public and private matters, will become a department manager.