What's the difference between quantity demand and demand?

What's the difference between quantity demand and demand? what's the difference between across and between? "demand" what is demand. what‘s the difference and similarity between fiction and non what's the difference between China's and Chinese? what's the difference between the words "bible" and "scriptu what's the difference between "sit" and "seat"? what's the difference between peanut butter and jam? what's the difference between sport and sports what's the difference between Chinese novels and western nov What's the difference between Chinese movies and western mov what's the difference between management and leadership?