X-ray machine vs apparatus

X-ray machine and apparatus both are nouns.

Word	Noun	Adjective	Verb	Adverb
X-ray machine	Yes	No	No	No
apparatus	Yes	No	No	No

As nouns, apparatus is a hypernym of X-ray machine; that is, apparatus is a word with a broader meaning than X-ray machine:

Other hypernyms of X-ray machine include setup.

X-ray machine (noun)	apparatus (noun)
an apparatus that provides a source of X rays	equipment designed to serve a specific function
	(anatomy) a group of body parts that work together to perform a given function