Drug cartels are all about money, they're a business.. And in Mexico they kill soldiers, Judges, cops, just about anyone who gets in their way.. Here on this side of the border they don't kill Judges, cops, soldiers, etc. because they know doing that would put them out of business in a matter of months. As brutal as they are they're a business, and they know killing Americans here would put them out of business.
ISIS is not a business, they really don't have anything to lose. Most religions, including Islam teach you will be rewarded AFTER you die..IMO that makes them more dangerous.