international scale vs centigrade scale

international scale and centigrade scale both are nouns.

Word	Noun	Adjective	Verb	Adverb
international scale	Yes	No	No	No
centigrade scale	Yes	No	No	No

As nouns, international scale and centigrade scale are synonyms defined as:

international scale and centigrade scale: a temperature scale that defines the freezing point of water as 0 degrees and the boiling point of water as 100 degrees

Other synonyms of international scale include Celsius scale.

international scale (noun)	centigrade scale (noun)
a temperature scale that defines the freezing point of water as 0 degrees and the boiling point of water as 100 degrees	a temperature scale that defines the freezing point of water as 0 degrees and the boiling point of water as 100 degrees