nutrient agar vs culture medium

nutrient agar and culture medium both are nouns.

Word	Noun	Adjective	Verb	Adverb
nutrient agar	Yes	No	No	No
culture medium	Yes	No	No	No

As nouns, culture medium is a hypernym of nutrient agar; that is, culture medium is a word with a broader meaning than nutrient agar:

nutrient agar: any culture medium that uses agar as the gelling agent
culture medium: (bacteriology) a nutrient substance (solid or liquid) that is used to cultivate micro-organisms

Other hypernyms of nutrient agar include medium.

nutrient agar (noun)	culture medium (noun)
any culture medium that uses agar as the gelling agent	(bacteriology) a nutrient substance (solid or liquid) that is used to cultivate micro-organisms