Mile-High City vs capital of Colorado

Mile-High City and capital of Colorado both are nouns.

Word	Noun	Adjective	Verb	Adverb
Mile-High City	Yes	No	No	No
capital of Colorado	Yes	No	No	No

As nouns, Mile-High City and capital of Colorado are synonyms defined as:

Mile-High City and capital of Colorado: the state capital and largest city of Colorado; located in central Colorado on the South Platte river

Other synonyms of Mile-High City include Denver.

Mile-High City (noun)	capital of Colorado (noun)
the state capital and largest city of Colorado; located in central Colorado on the South Platte river	the state capital and largest city of Colorado; located in central Colorado on the South Platte river