rental vs transaction

rental and transaction both are nouns.

Word	Noun	Adjective	Verb	Adverb
rental	Yes	Yes	No	No
transaction	Yes	No	No	No

As nouns, transaction is a hypernym of rental; that is, transaction is a word with a broader meaning than rental:

rental: the act of paying for the use of something (as an apartment or house or car)
transaction: the act of transacting within or between groups (as carrying on commercial activities)

Other hypernyms of rental include dealing, dealings.

rental (noun)	transaction (noun)
the act of paying for the use of something (as an apartment or house or car)	the act of transacting within or between groups (as carrying on commercial activities)
property that is leased or rented out or let

rental (adjective)	transaction (adjective)
of or relating to rent
available to rent or lease