Answer: Cowardice is fearing something that one should not fear.

Such as fearing to say the truth or to forbid evil.

Bravery is prowess upon the truth, such as undertaking the mission of defending Islam and Muslims in the fields of Jihad.

The Prophet (may Allah's peace and blessings be upon him) used to say the following in his supplication: "Allāhumma innī a‘ūdhu bika min al-jubn" (O Allah, I seek refuge with You from cowardice). The Prophet (may Allah's peace and blessings be upon him) also said: "A strong believer is better and dearer to Allah than a weak believer, and there is good in both." [Narrated by Muslim]