agar vs culture medium

agar and culture medium both are nouns.

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

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

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 agar include medium.

agar (noun)	culture medium (noun)
a colloidal extract of algae; used especially in culture media and as a gelling agent in foods	(bacteriology) a nutrient substance (solid or liquid) that is used to cultivate micro-organisms
any culture medium that uses agar as the gelling agent