pendulum vs apparatus

pendulum and apparatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
pendulum	Yes	No	No	No
apparatus	Yes	No	No	No

As nouns, apparatus is a hypernym of pendulum; that is, apparatus is a word with a broader meaning than pendulum:

pendulum: an apparatus consisting of an object mounted so that it swings freely under the influence of gravity
apparatus: equipment designed to serve a specific function

Other hypernyms of pendulum include setup.

pendulum (noun)	apparatus (noun)
an apparatus consisting of an object mounted so that it swings freely under the influence of gravity	equipment designed to serve a specific function
	(anatomy) a group of body parts that work together to perform a given function