Let me freaking clear this up.
"Cancellation" is when the network tells the studio who makes the show that they don't want it any more, such as "Invader Zim". The network might let the studio finish off the current series giving the show a proper finale, or if the ratings are very low they might want it to be axed effectively immediately, giving the studio no point of finishing episodes in production, or not letting the studio air the final episodes. In some cases, the studio might instead of the network cancel the series, thinking it might have no profit.
"Finished" is when the studio decides to wrap up the show, giving time to finish the final episodes and write the scripts for the last episodes, such as "Friends". These are usually long running series, like "Everybody Loves Raymond". I hope this has cleared up the confusion of the meaning of cancellation.