What’s the difference between the logical and physical structure of a file? what are the advantages of not having an application program interact directly with the physical file structure?

In the computer storage memory, a logical file structure refers to a collection of files which are set-up in an organized way inside different directories, folders/sub-folders and storage volumes. While a physical file structure of a file refers to the physical storage place which are arranged linearly as an address space .

PART B:

It is important not to have application programs interacting directly with the physical file structure because they (Application programs) already have a logical view of the computer's secondary storage, so application programs can have faster maneuvering and access to stored data

the difference is right there dont you see it

answer inspecting packets in isolation from their context;