Provides a directory which acts as any other resource pack
Provides a directory which overrides all other assets with the same resource locations
Official assets can be downloaded automatically at startup from the official Mojang servers (Mojang's Brand and Asset Guidelines are not violated this way). Pack devs can do this via a JSON config, mod devs can use a builder via glowredman.txloader.TXLoaderCore#getAssetBuilder
Why should I care?
I am a player You probably shouldn't
I am a modpack dev Because you can easily ship assets with your pack, e.g. for Custom Main Menu
I am a mod dev Because you can use this to effortless use official assets from other versions (older and/or newer), without having to include them in your mod (and breaking Mojang's license by doing so)