fertiliser vs plant food

fertiliser and plant food both are nouns.

Word	Noun	Adjective	Verb	Adverb
fertiliser	Yes	No	No	No
plant food	Yes	No	No	No

As nouns, fertiliser and plant food are synonyms defined as:

fertiliser and plant food: any substance such as manure or a mixture of nitrates used to make soil more fertile

Other synonyms of fertiliser include fertilizer.

fertiliser (noun)	plant food (noun)
any substance such as manure or a mixture of nitrates used to make soil more fertile	any substance such as manure or a mixture of nitrates used to make soil more fertile