princess vs maharani

princess and maharani both are nouns.

Word	Noun	Adjective	Verb	Adverb
princess	Yes	No	No	No
maharani	Yes	No	No	No

As nouns, maharani is a hyponym of princess; that is, maharani is a word with a more specific, narrower meaning than princess:

princess: a female member of a royal family other than the queen (especially the daughter of a sovereign)
maharani: a great rani; a princess in India or the wife of a maharaja

Other hyponyms of princess include archduchess, crown princess, maharanee, princess royal.

princess (noun)	maharani (noun)
a female member of a royal family other than the queen (especially the daughter of a sovereign)	a great rani; a princess in India or the wife of a maharaja