telephone receiver vs earphone

telephone receiver and earphone both are nouns.

Word	Noun	Adjective	Verb	Adverb
telephone receiver	Yes	No	No	No
earphone	Yes	No	No	No

As nouns, earphone is a hypernym of telephone receiver; that is, earphone is a word with a broader meaning than telephone receiver:

telephone receiver: earphone that converts electrical signals into sounds
earphone: electro-acoustic transducer for converting electric signals into sounds; it is held over or inserted into the ear

Other hypernyms of telephone receiver include earpiece, headphone, phone.

telephone receiver (noun)	earphone (noun)
earphone that converts electrical signals into sounds	electro-acoustic transducer for converting electric signals into sounds; it is held over or inserted into the ear