Malus vs genus Malus

Malus and genus Malus both are nouns.

Word	Noun	Adjective	Verb	Adverb
Malus	Yes	No	No	No
genus Malus	Yes	No	No	No

As nouns, Malus and genus Malus are synonyms defined as:

Malus and genus Malus: apple trees; found throughout temperate zones of the Northern Hemisphere

Malus (noun)	genus Malus (noun)
apple trees; found throughout temperate zones of the Northern Hemisphere	apple trees; found throughout temperate zones of the Northern Hemisphere