pin money vs spending money

pin money and spending money both are nouns.

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

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

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

Other synonyms of pin money include pocket money.

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