button vs doorbell

button and doorbell both are nouns.

Word	Noun	Adjective	Verb	Adverb
button	Yes	No	Yes	No
doorbell	Yes	No	No	No

As nouns, doorbell is a hyponym of button; that is, doorbell is a word with a more specific, narrower meaning than button:

button: an electrical switch operated by pressing
doorbell: a push button at an outer door that gives a ringing or buzzing signal when pushed

Other hyponyms of button include bell push, bell, buzzer, horn button, mouse button, panic button, reset button.

button (noun)	doorbell (noun)
a round fastener sewn to shirts and coats etc to fit through buttonholes	a push button at an outer door that gives a ringing or buzzing signal when pushed
an electrical switch operated by pressing
a device that when pressed will release part of a mechanism
any artifact that resembles a button
a specific area or icon in graphical user interface systems that is clicked or pressed in order to select a command or perform an action
a female sexual organ homologous to the penis
a round flat badge displaying information and suitable for pinning onto a garment
any of various plant parts that resemble buttons

button (verb)	doorbell (verb)
fasten with buttons
provide with buttons