It is very unlikely that you may have heard of a R4 3DS. When you think of a R4 3DS, you have to get in the mindset of a computer emulator. There are many computer emulators out there, and most work just like the R4 3DS. An emulator is a program that allows you to play video games of a similar console on a foreign system. The R4 3DS is very similar to an emulator, but it has some significant differences. The R4 3DS is a flashcard, or SD card, that allows ROMS to be downloaded and played on a Nintendo 3DS. The process is identical to an emulator you download on a computer or smart phone. You have to download ROMS for an emulator, so that it can properly play video games.
In contrast, the R4 3DS works a bit differently. For starters, the R4 flashcard is just a modified SD card. Since a Nintendo 3DS cartridge looks almost indistinguishable to a micro SD card, it was more convenient to adequately formulate a SD to fit inside of a Nintendo 3DS. Moreover, the SD is customized where ROMS can be downloaded and loaded onto the Nintendo 3DS. These ROMS can then be played from a custom homebrew application that allows incompatible games to be played. This allows even old retro video games from the Super Nintendo, Nintendo, Nintendo 64, Gameboy, Gameboy Color, and Gameboy Advance to be played at ease. Also, the R4 3DS can even play the video games of its predecessors including the Nintendo DS and Nintendo DSI. The R4 3DS also constantly updates its firmware so that more games can be played. It also does this to bring about incognito to its anonymous developers.
Furthermore, there is another reason why the R4 3DS isn`t an emulator. An emulator is only designed to play games specifically made for the program. For example, a Super Nintendo emulator can only play Super Nintendo Games. Also, a Gameboy Advance emulator can only play Gameboy Advance games and so on. However, the R4 3DS can upload ROMS from multiple video game consoles using homebrew applications. For example, you can load a Super Nintendo game onto the R4 flashcard, and play it using a Super Nintendo emulator. This is much better and efficient than a single emulator because it allows multiple games of various video game consoles to be played using one program.
In essence, the R4 3DS may be able to play commercial games on a foreign system such as an emulator. However, the overall difference is that it allows multiple, as well as different games to be played on one system.