What Is the Legal Difference Between a US Citizen Committing

Multiple Choice

What is the legal difference between a US citizen committing armed robbery and a US enemy combatant fighting American forces on a foreign battlefield?

A) The robbery suspect used a gun,thus making it a civil matter.
B) The armed robber,it may be said,took up arms against the US Government.
C) The enemy combatant took up arms against the US Government.
D) There are no differences between the two.