'price-difference' is a compound of 'price' and 'difference'. 'price' originates from Old French 'pris' (from Latin 'pretium'), where 'pretium' meant 'value' or 'price'. 'difference' originates from Latin 'differentia', where 'differentia' (from 'differre') meant 'a carrying apart' or 'distinction'.

'price' passed from Latin 'pretium' into Old French as 'pris' and into Middle English as 'pris/price', eventually becoming modern English 'price'. 'difference' passed from Latin 'differentia' into Old French 'difference' and then into Middle English as 'difference', keeping a similar form into modern English. The compound 'price difference' developed in modern English by combining these two established words.

Individually, 'price' originally meant 'value' or 'worth' and 'difference' originally meant 'a separation or distinction'; together as 'price difference' the term came to mean specifically 'the numerical gap between two prices'.