Here is a spoiler for Anchorman 2: Ron Burgundy starts off with everything that he needs--his family and their love--but he throws it all away for something that he wants--a career. But by the end of the film, he gives up what he thought he wanted (carerr) because now he wants what he needs (family).
That's a classic film arc, where the character's wants and needs conflict at the beginning and align at the end. Or put another way: the character faces the same situation at the beginning and end, but changes his attitude/decision. This classic arc shows how the character grows and changes.
Now look at Hot Fuzz: At the beginning, P.C. Nicholas Angel is a hard-charging officer who never has fun and hates the idea of moving out to the countryside--where he is banished by the London police. At the end, Angel has more fun with his police work, has grown to care about other people in addition to his police work, and likes the idea of staying in the countryside.
So why is Hot Fuzz a much better movie? Part of it is simply that Anchorman 2 has sequel issues: you loved the news team fight in the first one, so they'll give it to you again, but bigger/sillier. That works for some jokes and not for other jokes. Or for characters: you loved Brick being dumb in the first movie, so here's a lot more of that. Or: you loved Chris Parnell and Fred Willard, so here's some more of them (even though they are given very little screen time).
But a lot of the difference is that Hot Fuzz makes its comedy more part of the characters/structure and less of the focus, whereas Anchorman 2 is just a joke-joke-joke machine. In that way, it's more like Airplane, which was willing to throw as many jokes as possible out there, hoping that a few would land. And so, not only do many of the jokes fall flat, but many of them feel extraneous to the actual storyline.
You can almost see this in the cutting, which is very fast and uneven in some ways: they filmed so many different versions of things, that when they put together the best jokes/episodes, the cuts don't entirely fit.