herb vs marjoram

herb and marjoram both are nouns.

Word	Noun	Adjective	Verb	Adverb
herb	Yes	No	No	No
marjoram	Yes	No	No	No

As nouns, marjoram is a hyponym of herb; that is, marjoram is a word with a more specific, narrower meaning than herb:

herb: aromatic potherb used in cookery for its savory qualities
marjoram: pungent leaves used as seasoning with meats and fowl and in stews and soups and omelets

herb (noun)	marjoram (noun)
aromatic potherb used in cookery for its savory qualities	pungent leaves used as seasoning with meats and fowl and in stews and soups and omelets
a plant lacking a permanent woody stem; many are flowering garden plants or potherbs; some having medicinal properties; some are pests	aromatic Eurasian perennial