What is the most defining head feature separating the Tawny Frogmouth from owls?

Answer

A massive, almost comically wide mouth or gape

The bird gets its name from its broad, flat, and stout bill structure, which creates a wide gape resembling that of a frog, contrasting sharply with the hooked beaks of true owls.

What is the most defining head feature separating the Tawny Frogmouth from owls?
birdanimalappearancecharacteristicFrogmouth