Yes, it's the difference between writing with pen and paper or on a typewriter, and using a word processor. Correcting an oil painting, and working in contemporary drawing software. Planning the annual company budget on paper, and using Excel. Composing on a sheet and using a modern music notation program--not to mention the full virtual orchestra you can hook to it.

In theory it's just an issue of convenience and speed. Yet from a scale onwards, these factors make all the difference in the world: I once read that if a young couple ever tried to make the necessary calculations to create the Mandelbrot set (probably the most famous fractal shape there is, based on a quite simple mathematical function) by hand, it would be several generations before it would be finished.

So a software outliner is not just a faster, more convenient way of doing outlines; it represents the reason you'd want to do them in the first place.

As obvious as it may have been, I also didn't consider it within the context of this thread. Yet it is indeed very relevant.