IR vs Inland Revenue

IR and Inland Revenue both are nouns.

Word	Noun	Adjective	Verb	Adverb
IR	Yes	No	No	No
Inland Revenue	Yes	No	No	No

As nouns, IR and Inland Revenue are synonyms defined as:

IR and Inland Revenue: a board of the British government that administers and collects major direct taxes

IR (noun)	Inland Revenue (noun)
a board of the British government that administers and collects major direct taxes	a board of the British government that administers and collects major direct taxes