Buckeye nuts and "conkers," the nuts from horse chestnut trees, are remarkably similar. This is because both trees, the American buckeye and the horse chestnut, belong in the same tree genus, Aesculus. There are about six species of buckeye trees and about a dozen species of horse chestnut. However, they all produce very similar-looking nuts.
Buckeye nuts are often slightly bumpy, as if three or more lumps were pushed together. Horse chestnuts are round or oblong, but they are not as bumpy as buckeye nuts.
Buckeyes begin chestnut-brown, but they darken to a milk chocolate color as they ripen. Horse chestnuts usually stay the same color, which is a dark chestnut brown with a reddish tint.
The center color in both types of nuts is a pale buff or sandy-like color. In comparison, this center color is usually larger in a buckeye than in a conker.
Horse chestnuts are primarily found in Europe and Asia, while buckeyes are primarily found in North America.
Buckeyes are mostly smooth to the touch, while horse chestnuts often have ridges that are easy to feel and sometimes can be seen. Sometimes these ridges are very slight.