I tried to search it on the net. Even found that one from Wikipedia but I think I need a more understandable explanation. I just want to know the difference of the two and can they be associated with each other.
"Telnet" is an "end application" which can be used to manage a system remotely, depending on the specific implementation.
VPN, generally, is an access technology which gets you to the remote system. You will still need some type of management application at that point.