The Switch version updates the original gameplay to suit a home console environment:
An file is the official format used for digital software on the Nintendo Switch. It is the equivalent of an installer or a digital download package from the Nintendo eShop. Players utilizing homebrew or custom firmware (CFW) use NSP files to install games, updates, and DLC directly onto their console's microSD card. 2. What does "JPN" Mean?
Adds online battle capabilities, which were not present in the original 3DS release. Technical Details (NSP and Region)
