radiology vs tomography

radiology and tomography both are nouns.

Word	Noun	Adjective	Verb	Adverb
radiology	Yes	No	No	No
tomography	Yes	No	No	No

As nouns, tomography is a hypernym of radiology; that is, tomography is a word with a broader meaning than radiology:

radiology: (radiology) examination of the inner structure of opaque objects using X rays or other penetrating radiation
tomography: (medicine) obtaining pictures of the interior of the body

Other hypernyms of radiology include imaging.

radiology (noun)	tomography (noun)
(radiology) examination of the inner structure of opaque objects using X rays or other penetrating radiation	(medicine) obtaining pictures of the interior of the body
the branch of medical science dealing with the medical use of X-rays or other penetrating radiation