Greetings

The most striking difference is that It. uses the same words of greeting both when people meet and when they part - this means that "Good morning" and "Goodbye" are both "Buongiorno" (and "Good evening" and "Goodbye" are both "Buinasera") in formal greetings, while "Hello/Hi" and "Bye" are both "Ciao" in informal greetings. For a clarification on the meaning of "formal/informal" in this context see

"Buon pomeriggio" ( Good afternoon) is seldom used - with the exception of radio and TV programmes. In most of Northern Italy we use "Buongiorno" until sunset; in other regions they start using "Buonasera" just after lunch. Besides, there are individual variations based on personal background and/or preferences.

"Buonanotte" ( Good night) and "Addio" ( Farewell) are used only in parting.