Protel is most commonly used for circuit diagrams, and Visio is most commonly used for block diagrams. Protel is more professional and requires a longer learning time. If it is just for drawing patent application documents in the electrical field, a Visio can complete the block diagram and circuit diagram. Visio was created by a Taiwanese company more than ten years ago and has now become a component of Microsoft Office. Many of its shortcut keys are the same as Microsoft Word, making it much easier to learn.