The "better" claim often refers to audio. The 138RAR folder usually contains a separate "RomFS" folder that replaces the Western soundtrack with the original Japanese arcade soundtrack. Think “Ultimate Battle” by Takayoshi Tanimoto playing continuously, rather than the generic instrumental loops.
, which includes various balance changes and DLC compatibility. "Update 138" : This usually refers to the 1.38 patch. ".rar" or ".nsp" dragon ball fighterz nspupdate 138rar better
The extension signifies compression. In the world of file sharing and homebrew, a .rar file is a locked chest. It compresses the large NSP file for easier transfer and, crucially, it protects the data from corruption during download. The "better" claim often refers to audio