Similarities

• Since both products are made to do the exact same thing and both are two of the top brands in DS flash carts, the two are very similar. Both support Moonshell, which will allow for mp3, txt and certain types of video files to be played through the Nintendo DS. Both products feature superb game playback, easy drag-and-drop transfers, a cheat engine compatible with Action Replay. And both use Micro SD cards to actually store the data you put on them.
  
  

USB Micro SD Card Readers

• The USB micro SD card reader that comes with the M3 is more durable because it is made of metal. The one that comes with the R4ds is made of plastic and is still bigger than the M3's card reader. And the M3 card reader is spring loaded, meaning you can push down on it to release it as opposed to having to pull it out awkwardly, as with the R4 card reader.
  
  

What's Included?

• Both of the basic packages include almost the exact same things: the flash cart itself, a USB Micro SD card reader and a small plastic case for the flash cart. Though the R4ds comes with a disc, all it contains is firmware updates that are already out of date. It is recommended with both products that you visit the manufacturers' websites for the respective firmware upgrades, since they will always be up to date there.
  
  

Add-ons

• While the basic packages are nearly identical, the M3 Real triumphs as far as add-ons go. With the ability to purchase compatible rumble packs and ram extensions that go into the Nintendo DS's GBA slot, the M3 certainly has more to offer. Another huge bonus is that with the M3 you gain the ability to run GBA backups and roms, whereas with the R4 you are limited strictly to DS games.
  
  

Final Verdict

• Since both products are just about the exact same thing with different names, the final verdict only comes down to a few factors. For starters, if you're going with the basic bundle and don't want all the extra features available with the M3 then you should go with the cheaper R4, which you can get from $5 to $10 less than the M3. That said, if you'd prefer expandability, rumble and GBA support, you may want to go with the M3 Real and one of the packages including the extras.