When a user interacts with a TELNET client program, the terminal driver is responsible for translating the user's keyboard input and displaying output on the user's terminal or screen. It handles tasks such as converting keystrokes into network-friendly representations and interpreting received data to display it in a readable format.

On the other hand, the TELNET server receives incoming connections from TELNET clients and interacts with them. The server uses a network driver or network interface driver to handle lower-level networking tasks such as sending and receiving data over the network, managing network connections, and routing data between the client and server.

In summary, the TELNET client relies on a terminal driver for local input and output, while the TELNET server utilizes a network driver to handle networking-related tasks.

A pseudoterminal is a software emulation of a terminal device. In the case of a TELNET server, the pseudoterminal driver is responsible for emulating the terminal interface on the server-side, allowing the server to interact with the TELNET client as if it were a physical terminal.

The TELNET server uses the pseudoterminal driver to handle the translation of data between the network connection and the terminal interface. It manages input/output from the TELNET client, converts the data into a suitable format for the server's applications, and handles terminal-specific features and settings.

Therefore, to clarify, the TELNET server uses a pseudoterminal (pty) driver to emulate the terminal interface and interact with the TELNET client.