Singhalese vs Asian

Singhalese and Asian both are nouns.

Word	Noun	Adjective	Verb	Adverb
Singhalese	Yes	Yes	No	No
Asian	Yes	Yes	No	No

As nouns, Asian is a hypernym of Singhalese; that is, Asian is a word with a broader meaning than Singhalese:

Other hypernyms of Singhalese include Asiatic.

Singhalese (noun)	Asian (noun)
the Indic language spoken by the people of Sri Lanka	a native or inhabitant of Asia
of an ethnic group native to Sri Lanka

Singhalese (adjective)	Asian (adjective)
of or relating to the Sinhalese people	of or relating to or characteristic of Asia or the peoples of Asia or their languages or culture
of or relating to the Sinhalese languages