Loose-leaf tea is dried, large, individual loose tea leaves. Whereas the leaves used in most tea bags are the “dust and fannings” from broken tea leaves and are much smaller “leaves” than the whole leaves. When steeped, they release more tannins than whole loose-leaf tea, making the tea a bit more bitter in comparison. However, not all bagged teas are the same! Also, I like using bagged tea for cold brewing since cold brewing makes the tea taste less bitter in general.