bond rating vs valuation

bond rating and valuation both are nouns.

Word	Noun	Adjective	Verb	Adverb
bond rating	Yes	No	No	No
valuation	Yes	No	No	No

As nouns, valuation is a hypernym of bond rating; that is, valuation is a word with a broader meaning than bond rating:

bond rating: an evaluation by a rating company of the probability that a particular bond issue will default
valuation: an appraisal of the value of something

Other hypernyms of bond rating include evaluation, rating.

bond rating (noun)	valuation (noun)
an evaluation by a rating company of the probability that a particular bond issue will default	an appraisal of the value of something
	assessed price