cesium 137 vs caesium

cesium 137 and caesium both are nouns.

Word	Noun	Adjective	Verb	Adverb
cesium 137	Yes	No	No	No
caesium	Yes	No	No	No

As nouns, caesium is a hypernym of cesium 137; that is, caesium is a word with a broader meaning than cesium 137:

cesium 137: a radioactive isotope of cesium used in radiation therapy
caesium: a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal

Other hypernyms of cesium 137 include atomic number 55, cesium, Cs.

cesium 137 (noun)	caesium (noun)
a radioactive isotope of cesium used in radiation therapy	a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal