korien_feb20“She’s really shy, but her sister is so outgoing. They’re like night and day.” 「彼女はシャイなのに彼女の姉妹は外交面的。まるで昼と夜だね。」
“My cat is so much happier since we gave him a cat tree. It’s like night and day.” 「キャットタワーを与えたら猫が前よりすごく楽しそう。まるで昼と夜の違いみたい。」

ふたつのことがとても違う、もしくは真逆であることを「night and day」を使って表します。一つ目の例文では、姉妹なのに性格がとても違う女の子を比べます。二つ目の例文では同じ猫をある出来事の前後の状態を比べます。

When two things are very different, or complete opposites, in some way, we compare them to “night and day”. In the first example, we compare two girls whose personalities are very different even though they’re sisters. In the second example, the same cat is very different before and after a certain event.