A "broadcaster" puts a show out "on the air" (radio); nowadays, possibly over cable or internet. "Broadcasting" means specifically the act of transmitting it so that thousands of people can listen to it. You can have a program that is NOT broadcast. A "presenter" is a person who has prepared a presentation, a talk. It might be twenty minutes, it might be an hour. It might be illustrated with Powerpoint slides. In the most general meaning of the word, a "host" offers hospitality and a "guest" accepts it. If I give a party and provide food, I am the "host." The people who come and eat the food are the "guests." In the context of a talk or a meeting or a presentation, the "host" runs the show. As part of preparing the show, the host invites one or more "guests" to come participate. The "host" runs the show. The host speaks first: "I am pleased to welcome you here today..." The host introduces each guest. It is common to have a series of shows, all with the same host. "Rick Ferri hosts the Bogleheads on Investing podcast. Guests have included Dr. Wes Gray, Larry Swedroe, and Jonathan Clements." Often, the guests will be "presenters." The host introduces them, then leaves the platform and the presenter talks. There are other possibilities. Perhaps the host interviews the guest, and they have a conversation.