spending money vs pin money

spending money and pin money both are nouns.

Word	Noun	Adjective	Verb	Adverb
spending money	Yes	No	No	No
pin money	Yes	No	No	No

As nouns, spending money and pin money are synonyms defined as:

spending money and pin money: cash for day-to-day spending on incidental expenses

Other synonyms of spending money include pocket money.

spending money (noun)	pin money (noun)
cash for day-to-day spending on incidental expenses	cash for day-to-day spending on incidental expenses