The storage_path() function returns the absolute path to the storage directory, while Storage::path() returns the absolute path to a file within the storage directory.
In your case, since you have created a symbolic link to the storage/app/public directory, you can access files within that directory using either function. However, if you want to access files outside of that directory, you should use Storage::path().
To access the file /storage/app/public/Test/SubDir/Test.xlsx, you can use either of the following:
Storage::path('public/Test/SubDir/Test.xlsx');
or
storage_path('app/public/Test/SubDir/Test.xlsx');
Both of these will return the same absolute path to the file.
Note that storage_path() returns the path relative to the root directory of your Laravel application, while Storage::path() returns the full absolute path to the file.