loss vs diminution

loss and diminution both are nouns.

Word	Noun	Adjective	Verb	Adverb
loss	Yes	No	No	No
diminution	Yes	No	No	No

As nouns, diminution is a hypernym of loss; that is, diminution is a word with a broader meaning than loss:

Other hypernyms of loss include decline.

loss (noun)	diminution (noun)
the act of losing someone or something	the act of decreasing or reducing something
the disadvantage that results from losing something	the statement of a theme in notes of lesser duration (usually half the length of the original)
military personnel lost by death or capture	change toward something smaller or lower
the experience of losing a loved one
euphemistic expressions for death
the amount by which the cost of a business exceeds its revenue
something that is lost
gradual decline in amount or activity