Presentation Layer is the sixth layer in the #Open Systems Interconnection (OSI) Model. It mainly provides formatting services to the Application Layer such as file encryption and format conversion. Session Layer, Application Layer and itself are commonly known as Application Layer as a whole in Internet Protocol Suite (TCP/IP).
Functions such as #Encoding is done here.
Session Layer is the fifth layer in the #Open Systems Interconnection (OSI) Model. It manages the connections between hosts. Sometimes, it will referred to as Application Layer with Presentation Layer and Application Layer.
e2e occurs between the original source and the final destination, that is the encryption is happened in either Application Layer#, Presentation Layer#, Transport Layer# or Network Layer#. This implies that they have the shared keys. e2e only concerns about the encryption of the user data. If user’s privacy and security is desirable, then e2e is preferred. However, due to the translation limit when jumping between different network technology such as IPv4# and IPv6#, the data sent must be decrypted and then be transformed to an understandable form. This could be a huge compromise.
Encoding is done in Presentation Layer#.
Application Layer is the seventh layer in the #Open Systems Interconnection (OSI) Model. The main functionality for it is to provide networking services to user or application, for it to be ready to be sent down all the way down to Physical Layer. Networking engineers usually refer Session Layer, Presentation Layer and this layer as a single layer called Application Layer.