Formally
On the other hand, if you are talking to an unknown person, or someone who holds an honorable position like such as a teacher, priest, judge, or similarly important kind of person, there is a minor difference in how you greet them. You will have to make a small change in the way you say, 'How are you'. There will be a change to the verb 'estar', thus changing to, "¿Cómo está". The only difference is that the 's' gets knocked out.