Okay, imagine you are at a party. There is a person who greets everyone at the door, suggests where to get drinks and how to get to the dance floor. This person is the host. In other words, a host is someone who is responsible for making sure all guests are comfortable. Host is just the English word for the same thing.
Now, the hostess. Imagine you arrive at a restaurant and you need to find a place. A girl comes up, smiles warmly, and shows you where you can sit. This is the hostess — the person who takes care of the comfort of guests in a restaurant.
So, if a host or host is a general term for those who organize an event and are responsible for hospitality (comfort, etc.), then hostess often refers specifically to the restaurant or hotel environment.
