PODIUM and LECTERN
A PODIUM is a slightly raised platform that a public speaker stands on so that he may be seen when giving his speech. A conductor also uses a podium for visibility. Athletes stand on podiums when receiving their Olympic medals.
Depending on whom you ask, podium comes from the Greek word "podion" or "pothi/podi" (πόδι), meaning foot. You may have learned the root POD/PED at some point in school (meaning "foot." This can help you remember that PODIUM is something on which you put your foot. The plural form of podium is podiums or podia.
A LECTERN is the stand with the top (usually slightly slanted) on which a person puts his speech or notes. You stand behind the lectern and then place your items on the sloped surface.
Lectern first appears in the fourteenth century as lettorne/lettron, from the medieval Latin word lectrum, which in turn comes from the Latin word "legere" which means "to read." You find lecterns in any place where speeches or presentations are given, such as a classroom, auditorium, or church.
LECTERNS are often called podiums, but they are not interchangeable. You stand on a podium and stand behind a lectern.
You can give a speech with a lectern or without a lectern (think: improv). You can stand on a podium or not stand on a podium. You can stand on a podium AND use a lectern. But they are not interchangeable. One is the raised platform and one is the stand.