Over the years I've become used to polishing paint using 2 methods. While hand polishing is generally safer and more paint friendly (depending who you are) Machnine polishing can increase your production by quite a bit. We're talking cutting it in half at the very least.
Please note that I'm not speaking of those orbital buffers that you see for $30 at your local auto parts stores. I'm talking about high speed polishers. Buffers are mostly for either lazy people or people who may have injuries that force them to use those buffers. No offense to the lazy people, I feel your pain!
There are a lot of variables to consider when you decide to polish your vehicle. If you're new to detailing and you've never used a polisher and you have a nice paint job, then please consider sticking with hand polishing. It's so much more safer. Yes, it will take a bit longer, but you can be sure that you won't burn through your finish.
Machine polishing can be tricky and you can destroy your paint in a blink of the eye if you just go to town on your paint. This is why you must practice on a flat surface and get used to how the machine works.
But is there a difference between hand polishing and machine polishing as far as quality is concerned? Not really. If you take the time with hand polishing you can achieve the same results with either. The biggest difference between the two is the time you will save with a machine polisher, although a machine polisher can leave swirl marks. You'll have to learn how to get these out when you start using a machine.
Of course, a machine will run you several hundred dollars for a good polisher with all of the equipment. Now you may be able to find a cheaper, high rated polisher on Amazon, but make sure you read the reviews. Most of the time I have been involved in detailing the Mikita's were always tops on the list. Every shop I've worked at or run were using Mikita's. This doesn't mean you have to have a Mikita as these were at professional detail shops. Just find one that will fit your budget and won't harm your paint in the end.
Most people stick to hand polishing and some love it, some hate it. The choice always comes down to your preference. In fact, some cars just make you want to do everything by hand, whereas some give you the feeling that a machine is best. Time matters, but so does the paint that you can destroy if you're not sure how to handle a machine!
If you're new to polishing with a machine you need to make sure you get a Dual Action Polisher. These types of polishers are great for newbies as they will help protect you from making serious mistakes. When you start to use a dual action polisher you want to practice slowly and get used to the feel. Always make sure the paint is clean of dirt and debris (in other words: wash it good!) and dry it well.
Start off in a flat area (hood) and gently get the polisher moving. Use a small amount of material at first and just get used to everything. Don't stay in one spot and don't press down on the paint too hard. You basically want to apply a very small amount of pressure, enough to get the head of the polisher onto the paint and go in a back and forth motion. With a dual action machine, you don't have to worry too much about applying too much pressure as it should help prevent you from doing any damage and creating too much heat. But that doesn't mean you want to test that feature out on your paint.
Always read the manual that comes with your polisher as it will give you some sound advice for how to use that specific machine. There are most likely decent youtube videos that will show you how to use a polisher also. Just make sure you don't go all out your first time using one. Be careful and watch what you're doing at all times!