There are many types of campaigns. Some are big, some are small, some are episodic and some are one long story that stretches for years with no breaks out of it. There are those dungeons who take the characters from level 1 to 15 and then a little more and those campaigns who take the characters from level 1 to 5 with 2 little adventures within it to call it a campaign.
There are those campaigns in which each session is a complete adventure, with different enemies and goals. "Today, you have to collect the sheets of Amon-Ra", Yesterday they had to kill Shamalanious. The only connection between the adventures in this campaign is the main cast of protagonists. It's the same Spoke and the same Luke and the same Castle. If there's character advancement, it's small and not that grandiose. There are no weddings or childbirths, no funerals of the characters' parents, and the characters need years to advance emotionally.
There are also those campaigns in which each session is a complete adventure, except for a few 2-times to advance the plot even further. There's a clear big bad in the end, but there are breaks from him (or her) every few session to bring anticipation for the comeback of the big bad. The characters advance a lot, getting friends and losing them, getting closer to some ones and losing them and so on. The main cast of Buffy and Angel and many more is suddenly getting the help of Angel who turned into Angelus, they have suddenly the need to confront the big bad Geppetto and so on. Still a main cast, but there's also the main villain.
There are also the campaign that stretches for years, without clear ending, that just grow bigger and bigger in years, with the same big bad in the end, even after so many years, and no breaks to clear the mind have been seen since the campaign started. Neo still has to fight Agent Smith, even after so many years, and since the second age they are still trying to defeat Sauron. One day it may end, but 'till then there's no other choice but to keep getting closer to this end point.
And there are of course many campaigns that fall between the lines, between the walls of imaginary "no-trespassing", maybe parodying or maybe trying to advance those walls to save the games from becoming all too similar patterns. Campaigns in which each act is in a different style, campaigns in which every act has a different director or GM and so on...
How about your campaigns? To where do they fall? Do they have a category of their own?