They're not the same, even though they're often confused with each other since they have a similar appearance. In the Mediterranean, oregano is also known as wild marjoram, but that doesn't mean the two are related. To make matters more confusing, marjoram's botanical name is in the same genus as oregano, but it's a completely different species. Marjoram has a gentler lemony-like flavor and is sweeter than oregano. It also doesn't have quite as strong of an aroma. However, if you find that you are out of marjoram, you can substitute oregano in the dish.