Are there differences? HELL YES! BIG
ones. If you are using a cheapie Chinese Red Army store da you will want to smash it with a hammer once you start using a quality tool. Right off the bat most use MUCH less air so they are way more powerful. I have a HF (Chinese Red Army) die grinder I bought for a particular tool that seldom used and didn't want to have to change it out of my good die grinder while doing this stuff for a living (I have four die grinders with the different tools, two drills dedicated to certain bits, etc.)
This tools job was very simple, it really didn't need much power to get it done, it SUCKS and barely just barely can do it. My similar quality die grinders would kick it's ever loving butt.
There is nothing that makes more sense to me than buying quality tools. If you do it for a living, for God's sake do I have to tell you? But if you are doing this stuff at home, the learning curve is steep enough doing this stuff do you really want to have to overcome using the junk tool too? Do you know what your HF da is worth after you bring it home from the store? NOTHING, you couldn't sell a used HF tool for a dollar. How about a National Detroit Da, it costs about $150-190 how much is it worth ten years from now if still in good condition? You could STILL sell it for $100 or something on ebay. If you bought that tool 25 years ago when they WERE about $75 you could sell it for what you paid for it!
There are all kinds of brands that will do the job for you. Here is what I used every day for years upon years doing it for a living.
"Hog" as Tech mentioned. A ND (National Detroit) 900 is THE tool for cutting filler and stripping paint. When mine broke (after about 10 years of daily service) I wouldn't live a day without it, I bought a new one then sent the old out for rebuild. Now I have two and never have to worry about being without one. I don't know what kind of deal you can get but here is one for $185.00 (Clickhere)
This tool is literally an 8" block. You can cut filler flat like a block with this tool, it is a WORKHORSE tool that I wouldn't live without.
For a "DA" the National Detroit "DAQ". This is THE workhorse DA of all time. Again, used one for a couple of decades just about daily rebuilding it once in a while, they are a SUPER tool. Here's one for $165 (click here)
This is a REAL "DA" (Dual Action) being that it has a little lock that you flip for changing it from an orbial sander into a grinder with the disc spinning without an orbit. Again, it is a work horse, aggressive sander and NOT for finish sanding, at least not anymore. There was a day when that is exactly what it was used for. It is the grandfather of the DAs. I use mine in the grinder mode for metal finishing only these days (repairing without the use of any filler) being I have other orbital sanders for doing paint prep work.
Then the "Orbital" for finish sanding and sanding primer and the like. I have had one of these DynaBrades for years and it has given me ZERO problems.
Here is one for $185. (click here)
This is not a "Dual action" in that it only orbits. This is where the different orbit patterns comes into play, the smaller the more for finishing. Picture this as a 6" "block" it works THAT good. With some use you can "block" filler perfectly flat with this baby, it's a great tool.
All of these tools blow away anything at HF. They would stomp on them in comparison.