How do you separate horror from science fiction?
Any scientist that makes himself invisible or creates a creature or flies to moon in a sphere or a giant made from radioactive fallout; no matter what horrors we see in the picture; is Sci Fi.
So what is the Terminator? Sci Fi But, a lot of shooting. I guess, stabbing/total dismemberment separates action/sci fi from horror. If a good old Anglo Saxon gun used, its Action.