alkaline metal vs alkali metal

alkaline metal and alkali metal both are nouns.

Word	Noun	Adjective	Verb	Adverb
alkaline metal	Yes	No	No	No
alkali metal	Yes	No	No	No

As nouns, alkaline metal and alkali metal are synonyms defined as:

alkaline metal and alkali metal: any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium)

alkaline metal (noun)	alkali metal (noun)
any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium)	any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium)