Family and genus differences: Amaryllis is a plant of Amaryllidaceae, and Lilium is a plant of Lilium in Liliaceae. Different colors: red is the main color of red, mostly variegated, while the color of lily is mostly white. The flower stems are different: the red ones are thicker, while the lilies are thinner. Leaves are different: the leaves are longer, growing from the bulbs. Lily leaves are shorter and grow from the stems.

The difference between red and Lily
The difference of flowers

The difference of flower stem
Different leaves
