Which feature sets the Elf Owl apart from many other North American owl species according to field guides?

Answer

Lack of ear tufts

A subtle but important feature often noted in field guides is the lack of ear tufts, which distinguishes the Elf Owl from many other owl species.

Which feature sets the Elf Owl apart from many other North American owl species according to field guides?
birdanimalwildlifecharacteristicowl