Ferns and mosses are both examples of "primitive plants," according to J. Stein Carter of the University of Cincinnati Biology Department. They have not developed all the specialized systems that modern plants have, although ferns are more highly developed than mosses.
Mosses are not well adapted to living on dry land. Ferns do better at it. This is largely because while mosses do not have a vascular system, ferns do.
Fern spores are produced in clusters underneath the leaves. Moss spores are produced in capsules on the tips of stalks among their shoots.
Ferns have large compound leaves divided into many leaflets. Mosses have no true leaves, just tiny green shoots. Some ferns can grow higher than 15 feet. Mosses are limited to about an inch.
Club mosses have tiny true leaves with vascular systems. The extinct Lepidodendron was a giant club moss that looked like a tree. It could grow over 135 feet high.