Warfare is when there is a struggle or battles or organized fighting between enemies (which could be countries or peoples).

Military operations between enemies : hostilities, war; also : an activity undertaken by a political unit (such as a nation) to weaken or destroy another.

Source: https://www.merriam-webster.com/dictionary/warfare 

 

La guerre – La guerre fait référence à un conflit ou à un combat entre des groupes ou des pays.