"Greetings" and "hello", what are the different ways to use that?
"Greetings" means "hello", but it is very old-fashioned and formal. "Greetings" is also a word that is often associated with aliens and outer space, because Hollywood has used the term "greetings" in many movies with aliens. So the word "greetings" sounds a little more technical, informal, and unnatural than "hello". Most native speakers will never use the word "greetings" to greet someone. Ex: Greetings, earthlings!