Telnet and FTP are both types of IP protocol. Telnet allows a user to issue commands remotely. A user can log in to the remote server to access resources. Telnet is not as secured as FTP. The port number of telnet is 23. Telnet can translate NVT from data and also able to convert it into accepted form.
FTP stands for File Transfer Protocol. It allows the transfer of files to a remote location. FTP can transfer data from server to client. For you to access FTP, remote login is required. FTP is more secure and a lot safer than telnet. The port number of FTP is 20.
FTP is the one that is used when you want to copy one file from one machine to another machine easily. Telnet, on the other hand, is the one that you will use when you need to access data from another server remotely. It is obvious that these two are used for different purposes.
FTP is also known to be used with a command line or with the help of a dedicated application. Telnet can only be used at the command line and cannot be used anywhere else. When you are using FTP, there is no need for you to log in to the machine that you are using, but when you are using Telnet, you still need to log in to get the needed data.