areca vs betel palm

areca and betel palm both are nouns.

Word	Noun	Adjective	Verb	Adverb
areca	Yes	No	No	No
betel palm	Yes	No	No	No

As nouns, betel palm is a hyponym of areca; that is, betel palm is a word with a more specific, narrower meaning than areca:

areca: any of several tall tropical palms native to southeastern Asia having egg-shaped nuts
betel palm: southeastern Asian palm bearing betel nuts (scarlet or orange single-seeded fruit with a fibrous husk)

Other hyponyms of areca include Areca catechu, Areca palm.

areca (noun)	betel palm (noun)
any of several tall tropical palms native to southeastern Asia having egg-shaped nuts	southeastern Asian palm bearing betel nuts (scarlet or orange single-seeded fruit with a fibrous husk)