What is the difference about militia men and minutemen?

Militia existed in the colonies long before the American Revolution. With the exception of Pennsylvania, colonies required most able-bodied men to own weapons, to be willing to be called for periodic training, and to defend their communities from attack, primarily by Indians. This was the colonial militia.

Minutemen came into being in the wake of the crisis in Boston, in 1774. Essentially, they were a reorganized militia, rid of any vestiges of loyalty to the crown, and trained, far more extensively than they had been previously, so that they could "turn out" at a minute's notice.