X-ray vs myelogram

X-ray and myelogram both are nouns.

Word	Noun	Adjective	Verb	Adverb
X-ray	Yes	No	No	No
myelogram	Yes	No	No	No

As nouns, myelogram is a hyponym of X-ray; that is, myelogram is a word with a more specific, narrower meaning than X-ray:

X-ray: a radiogram made by exposing photographic film to X rays; used in medical diagnosis
myelogram: X-ray film of the spinal cord and spinal nerve roots and subarachnoid space

X-ray (noun)	myelogram (noun)
a radiogram made by exposing photographic film to X rays; used in medical diagnosis	X-ray film of the spinal cord and spinal nerve roots and subarachnoid space
electromagnetic radiation of short wavelength produced when high-speed electrons strike a solid target