Yes, there is such a thing as a "professional" tractor versus an "amateur" tractor. Most residential customers who live in the country don't want to spend the money for a regular, heavy duty piece of farm machinery, so they opt for a smaller, lightweight tractor to plow their garden patches.
Similarly, if you go to any hardware store, you will find a wide range of power tools. For example, a professional contractor will probably spend several hundred dollars on a quality power tile saw, whereas the DIY homeowner will be more likely purchase a cheap saw for fifty bucks.
The cheap saw won't stand the test of time, but it will suffice for a few tile jobs around the home.
Finally, why is a protractor called a protractor? Because that is the name given to a device used to measure angles. There are many types of protractors, depending on what you plan to do.
A drafter uses a flat protractor for drawing whereas a carpenter uses one with two edges and a dial or digital angle indicator to measure corners.