Question: What is the difference between row covers and landscape fabrics?

Answer: Row covers are intened to be used over plants to protect them from cold or to exclude pests. There are different weights of fabric depending on the need -- heavy fabrics offer the best protection from the cold, while light ones are best for insect control so the plants don't heat up too much underneath. Landscape fabric is intended to be used on the soil surface to block weeds. Although I suppose that, in a pinch, you could swap uses, it's probably best to purchase the correct material in the first place. For example, black landscape fabric used as a row cover might cause the plants underneath to overheat.