Schopenhauer obviously learns from the German Idealists tradition of assuming an unconscious force acting on the world (or "underneath" it), but Schopenhauer's take is that this force is a blind will, the World Will, that acts amorally, without any certain agenda. Schelling’s idea in the System of Transcendental Idealism is quite similar, but I'm not exactly sure if Schelling's Absolute is a blind one, as it strives to "know" itself. Maybe the its creations are created "blindly", but I'm not sure the force itself is exactly "blind" as Schopenhauer's pessimism view suggests.
Any help with this? I'm thinking maybe it's the same idea, but Schopenhauer's pessimism is the defining separation between the both. Do note that I'm talking about the System of Transcendental Idealism in Schelling, not his later writings when he goes to the more spiritual theistic approach.