That difference is understanding processes involved, visualizing the finished product and planning for success. Basically experience equals quality. Of course these days anything to do with print is competitive; producing your annual report there’s always a small copy shop that will undercut a dependable print shop, designing a flyer there’s always a “designer” with Photoshop who will low-ball a seasoned graphic design professional.

Looking at a layout on screen isn’t picturing the final project. Quality print design is thinking of the end product at a projects conception and those are lessons learned the hard way. You can learn those lessons for yourself but unless that’s your chosen career path why would you need to?