all bark and no bite

idiomatic not-comparable

Japanese Meaning

口先だけで大言壮語するが、実際には力や本質が伴わない / 鋭い言葉を発するが、実は内面は温厚である

His threats are all bark and no bite; he talks tough but never follows through.

彼の脅しは口だけで行動が伴わず、強気なことを言うだけで決して実行しない。

Sense（1）

(idiomatic) Full of big talk but lacking action, power, or substance; pretentious.

Sense（2）

(idiomatic) Often making cutting remarks, but having a gentle personality underneath.

Sense（3）

(idiomatic) Aggressive but never combative.