적다, 작다 ??? what's the difference?

적다 - you can use this when you compare numbers. less. little. few. etc.
작다 - size. small/short

더 낮다 - lower
더 낫다/더 좋다 - better
더 안 좋다/더 나쁘다 - worse

더 높다 - higher
더 크다 - taller , bigger

*낫다 and 낮다 are pronounced the same.