rr

As an initialism rt

is .

As a noun rr is

railroad.

As a proper noun rr is

roraima, a state of brazil.

As an abbreviation rr is

(aviation|travel|dated) (from the status code used in the gds) reconfirm / reconfirmed.

As proper nouns the difference between rr and jj

is that rr is roraima, a state of Brazil while JJ is a male given name, often short for Jacob.

As abbreviations the difference between rr and jj

is that rr is (from the status code used in the GDS) reconfirm / reconfirmed while JJ is judges or justices, used after a list of names (singular J).

As a noun RR

is railroad.