What's the main difference between being "small" and "compact?"

Native speaker’s answer
Rebecca
In this context, to be "compact" means to take up little space (compared to other things) or to be neatly arranged in a small space. It's usually used in a positive way to express the utility and convenience of something that is small. In comparison, "small" is an adjective used to describe size only. Ex: This backpack is too small to fit all my books. Ex: The company is trying to develop a smaller-sized battery. Ex: My portable battery is compact and convenient to carry around. Ex: For people living in highly-populated cities, a compact car is a better choice than SUVs or larger car models.