keypad vs input device

keypad and input device both are nouns.

Word	Noun	Adjective	Verb	Adverb
keypad	Yes	No	No	No
input device	Yes	No	No	No

As nouns, input device is a hypernym of keypad; that is, input device is a word with a broader meaning than keypad:

keypad: a keyboard that is a data input device for computers; arrangement of keys is modelled after the typewriter keyboard
input device: a device that can be used to insert data into a computer or other computational device

Other hypernyms of keypad include data input device, keyboard.

keypad (noun)	input device (noun)
a keyboard that is a data input device for computers; arrangement of keys is modelled after the typewriter keyboard	a device that can be used to insert data into a computer or other computational device