spending vs expenditure

spending and expenditure both are nouns.

Word	Noun	Adjective	Verb	Adverb
spending	Yes	No	No	No
expenditure	Yes	No	No	No

As nouns, expenditure is a hyponym of spending; that is, expenditure is a word with a more specific, narrower meaning than spending:

Other hyponyms of spending include expending, compensatory spending, deficit spending, pump priming.

As nouns, spending and expenditure are synonyms defined as:

Other synonyms of spending include outgo, outlay.

spending (noun)	expenditure (noun)
the act of spending or disbursing money	the act of spending money for goods or services
money paid out; an amount spent	the act of consuming something
	money paid out; an amount spent