fodder vs alfalfa

fodder and alfalfa both are nouns.

Word	Noun	Adjective	Verb	Adverb
fodder	Yes	No	Yes	No
alfalfa	Yes	No	No	No

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

fodder: coarse food (especially for livestock) composed of entire plants or the leaves and stalks of a cereal crop
alfalfa: leguminous plant grown for hay or forage

Other hyponyms of fodder include eatage, forage, grass, pasturage, pasture, broad bean, horse bean, hay, stover.

fodder (noun)	alfalfa (noun)
coarse food (especially for livestock) composed of entire plants or the leaves and stalks of a cereal crop	leguminous plant grown for hay or forage
soldiers who are regarded as expendable in the face of artillery fire	important European leguminous forage plant with trifoliate leaves and blue-violet flowers grown widely as a pasture and hay crop

fodder (verb)	alfalfa (verb)
give fodder (to domesticated animals)