Improvement of Note on Fetchers

source/tutorials/nix-language.md

@@ -1878,7 +1878,17 @@ builtins.fetchTarball "https://github.com/NixOS/nix/archive/7c3ab5751568a0bc6343
 ```
 
 :::{note}
-The Nixpkgs manual on [Fetchers][nixpkgs-fetchers] lists numerous additional library functions to fetch files over the network.
+Nixpkgs provides its own fetcher functions to reduce the time needed for evaluating Nixpkgs. The Nixpkgs fetchers are not directly interchangeable with builtin fetchers; for example, the Nixpkgs fetchers require a hash argument.
+
+:::{note}
+Nixpkgs provides its own fetcher functions with important differences from the builtin fetchers:
+
+- Nixpkgs fetchers require a hash argument for better reproducibility
+- They support more protocols and source types (Git forges, SVN, CVS, etc.)
+- They are not directly interchangeable with builtin fetchers
+
+See the Nixpkgs manual on [Fetchers][nixpkgs-fetchers] for the complete list and detailed usage information.
+:::
 :::
 
 It is an error if the network request fails.