Characteristic, trait, feature mean something that marks or sets apart a person or thing.
Characteristic designates a constant property or quality that stands out in such a way as to distinguish a person or thing from others or to reveal him or it as he or it is; the term is applicable not only to persons and concrete objects but to things which are immaterial, intangible, or the product of abstraction.
Trait applies especially to persons, peoples, or types and to their sharply accented qualities of character or of mind; otherwise, the term differs from characteristic only in its suggestions of clear definition and of distinctiveness.
Feature, on the other hand, suggests not a quality or property, but a part or detail of a thing (as a face, a view, an object, or a character) which attracts and holds the attention by reason of its shape or form or by reason of its importance, its conspicuousness, or its being pressed upon one’s attention.
In the United States the term feature is often applied specifically to something exhibited or advertised as particularly attractive and especially to the principal attraction in a motion-picture entertainment or to a distinctive or prominent article, story, or cartoon in a periodical.