The greatest barkers are not always the sorest biters.

A noisy display of aggression does not reliably show how much harm someone can or will cause. Threats and bluster may amount to less than they suggest.

The proverb advises judging danger by more than outward noise. Its qualification matters: a person who makes loud threats might still act on them.

Use it when someone assumes that the most vocal critic or opponent poses the greatest threat. It encourages attention to what people do and are capable of doing, rather than to how loudly they speak.