You use the word 'greetings' to relatives/people you know well and 'regards' to work colleagues or aquaintances.

They can mean the same thing, but it is subtle. For example, I might say, "Give my regards to your mother." What I mean is, "Tell your mother I said 'Hello.'" But, for example, in your opening sentence, if I meant, "I want to greet mt friends," I would never say, "I want to regard my friends." If I were speaking to a third-person, who might speak to my friends before I do, I could say, "Give my regards to my friends." Does that make any sense?

Greeting:the act of meeting someone Greet:to meet someone Regard:consideration

Greeting :- A polite word or sign of welcome or recognition. Regards : - A formal request to consideration for someone or something. these words can be used for a time or on a situation. It's just all about the time references.