boron fertiliser vs fertilizer

boron fertiliser and fertilizer both are nouns.

Word	Noun	Adjective	Verb	Adverb
boron fertiliser	Yes	No	No	No
fertilizer	Yes	No	No	No

As nouns, fertilizer is a hypernym of boron fertiliser; that is, fertilizer is a word with a broader meaning than boron fertiliser:

boron fertiliser: a plant fertilizer which formula contains boron.
fertilizer: any substance such as manure or a mixture of nitrates used to make soil more fertile

Other hypernyms of boron fertiliser include fertiliser, plant food.

boron fertiliser (noun)	fertilizer (noun)
a plant fertilizer which formula contains boron.	any substance such as manure or a mixture of nitrates used to make soil more fertile