Evening is the time when the sky starts to get dark – usually around 6-8 PM.
Night is the time when it is dark and people are generally sleeping.

Good Evening

Say “Good evening” to say “hello” after 6:00 PM. “Good evening” is commonly used at restaurants, in a professional context, and in speeches (when you speak in front of a large number of people):

• “Good evening, do you have a reservation?” (at a restaurant)
• “Good evening, Tom. How are you?” (to a colleague)
• “Good evening, ladies and gentlemen…” (in a speech)

In general, “good evening” is a little more formal. Friends don’t normally say “good evening” to each other – they would say “Hi”, “What’s up?” or another informal greeting.

Good Night

Say “Good night” to say “goodbye” – when you are leaving to go home. Family members also say “good night” when they are going to bed.

• “Good night, Janet. See you tomorrow.”
• “Good night, mom. I’m going to bed.”

Veja os exemplos abaixo extraídos, da abertura e do encerramento de dois programas de televisão.

• Hello, good evening and welcome: The David Frost story. Sir David Frost is famous the world over for his interviews with presidents and prime ministers, but his journalistic side is just one part of his repertoire. (BBC)
• Olá, boa noite e sejam bem-vindos: A história de David Frost. Sir David Frost é internacionalmente conhecido por suas entrevistas com presidentes e primeiros-ministros, mas o jornalismo é apenas uma de suas várias facetas.
• Thank you so much to all of our guests, to you at home for being with us. We’ll see you tomorrow night, 8:00 sharp Eastern. Good night, everybody. (CNN)
• Agradeço aos convidados pela presença e a vocês em casa pela audiência. Até amanhã às 20h em ponto (no horário da costa leste). Boa noite a todos.