hanging geranium vs Pelargonium peltatum

hanging geranium and Pelargonium peltatum both are nouns.

Word	Noun	Adjective	Verb	Adverb
hanging geranium	Yes	No	No	No
Pelargonium peltatum	Yes	No	No	No

As nouns, hanging geranium and Pelargonium peltatum are synonyms defined as:

hanging geranium and Pelargonium peltatum: a commonly cultivated trailing South American plant with peltate leaves and rosy flowers

Other synonyms of hanging geranium include ivy-leaved geranium, ivy geranium.

hanging geranium (noun)	Pelargonium peltatum (noun)
a commonly cultivated trailing South American plant with peltate leaves and rosy flowers	a commonly cultivated trailing South American plant with peltate leaves and rosy flowers