I used to think valor is for combat and merit is non-combat. Then I realize Purple heart, a successor of Badge of Military Merit, is awarded for "being wounded or killed in any action against an enemy", which I understand as combat. However, I also see medal citation using phrases like "extraordinary fidelity" or "exemplary conduct" to describe recipient of non-valor bronze star medal, which I understand as non-combat. So, is merit combat or non-combat?
the quality of being particularly good or worthy, especially so as to deserve praise or reward.
great courage in the face of danger, especially in battle
As we readily see, merit describes skill, and valor describes bravery. These qualities, both praiseworthy, are not even close to being synonyms.
In ordinary parlance acts of valor would only be possible in combat, in the face of the enemy or other extreme danger. However acts of merit would not require such extreme personal danger, and frequently refer to much longer time frames than would generally be inspected for battlefield valor.
In the U.S. military:
In 1932, the United States War Department authorized the new Purple Heart Medal .... At that time, it was also determined that the Purple Heart Medal would be considered the official "successor decoration" to the Badge of Military Merit.