Moss is a plant; lichen is not a single plant at all but algae and fungi growing together as one organism. If it is soft, green and carpet-like, it is moss; if it is crusty, pale or greenish and stuck flat to a rock or wall, it is lichen.
The core difference
Moss is a true plant, while lichen is a partnership between algae and fungi.
- moss — a small, soft green plant without flowers that grows in damp places: Moss covered the north side of every tree in the forest.
- lichen — an organism formed by algae and fungi living together, often seen as pale or greenish patches on rocks, trees or walls: Thick lichen covered the old stone wall.
How to tell them apart
A quick memory hook: moss feels soft and springy, almost like a tiny plant carpet, because it is a plant. Lichen feels dry, crusty or leathery, because it is fungus and algae fused together rather than a single growing plant.
The two often turn up in the same damp, shaded spots, so people mix them up on the same wall or tree trunk. Scientists also pay attention to lichen specifically because it is sensitive to air pollution, which is not something said of moss.
