PIN number vs personal identification number

PIN number and personal identification number both are nouns.

Word	Noun	Adjective	Verb	Adverb
PIN number	Yes	No	No	No
personal identification number	Yes	No	No	No

As nouns, PIN number and personal identification number are synonyms defined as:

PIN number and personal identification number: a number you choose and use to gain access to various accounts

Other synonyms of PIN number include PIN.

PIN number (noun)	personal identification number (noun)
a number you choose and use to gain access to various accounts	a number you choose and use to gain access to various accounts