debtor vs mortgager

debtor and mortgager both are nouns.

Word	Noun	Adjective	Verb	Adverb
debtor	Yes	No	No	No
mortgager	Yes	No	No	No

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

debtor: a person who owes a creditor; someone who has the obligation of paying a debt
mortgager: the person who gives a mortgage in return for money to be repaid

Other hyponyms of debtor include deadbeat, defaulter, fly-by-night, mortgagor.

debtor (noun)	mortgager (noun)
a person who owes a creditor; someone who has the obligation of paying a debt	the person who gives a mortgage in return for money to be repaid