Welcome the audience using serious language for a formal occasion
Pick an appropriate greeting such as
Good evening ladies and gentlemen
Then welcome the audience to the event using a phrase such as
It is my pleasure to welcome everyone to our beautiful venue tonight
Keep the tone more serious if it's an important occasion
Use more formal language and don't crack any inappropriate jokes
For example, at a wake, you might say
We're so glad to have you all here tonight
We appreciate your presence at this difficult time
Greet guests informally by using light-hearted language
Choose a simple and straightforward greeting such as, Good morning everyone express your gratitude towards the guests for attending by using a phrase such as
It's so wonderful to see you all here on this sunny day
For an event with close friends and family
More informal language might be appropriate
Include a few jokes and keep your speech more lighthearted