Garden-Marjoram (Origanum majorana) is a one or two-year herbaceous plant. All of above-ground parts are rich in essential oils and used as a herb. It is also called "Spanish hops" because of its charmed flowers similar to the hops.
Origanum majorana is the spice we call Merian, while its very close cousin Origanum vulgari is the spice we call oregano.
Marjoram is mild and delicate in flavor, while oregano is strong and distinct taste.