Marjoram is an herb that's closely related to oregano and tastes very close but they're different herbs. I remember reading years ago that most people use marjarom to season foods, and think it's oregano.

I use a lot of marjarom in cooking - not as much oregano - but I do like to use the Greek oregano - it has a nice flavor. (even though I am Italian)

I think what turned me off to oregano was many years ago when the pizzerias used to load oregano on their pizza trying to make them "Italian" style. Many Italian pizzas don't even have oregano on them! Depends on the region you are from.