Every company has their major event the one that they spend the entire year building to and always try to put the best foot forward. To state the obvious Wrestle Kingdom is New Japan's biggest event of the year & WWE's biggest event of the year is WrestleMania. Typically the build for Wrestle Kingdom usually sees many of the top feuds come to a head and very rarely if ever does the pay off disappoint. The same could said for WrestleMania, but in a different way as the feuds that culminate at WrestleMania very rarely have the build that matches at Wrestle Kingdom do. Now I know that not every feud needs to be built up for a year, but sometimes we also see years of build culminate at the event.
We could look no further to see the build then this years main event at Wrestle Kingdom 12 with Tetsuya Naito & Kazuchika Okada colliding in the rematch that had three years of build. For those who don't know Naito actually lost the main event of Wrestle Kingdom that he won from winning G1 Climax due to Fan Vote. This lead to IWGP Intercontinental Champion Shinsuke Nakamura vs Hiroshi Tanahashi headlining the event instead of the World Title. Within that year Naito would end up leaving for Mexico to find himself and get sort of a reset to his character. However, this Wrestle Kingdom event did end up leading to the start of the feud between Okada & Naito that hit another milestone at this years event. Either way though this happens all time with matches at this event and to give one other example look no further then Okada & Tanahshi's set of matches they had at the event.
It is pretty to me that the main difference between Wrestle Kingdom and WrestleMania is the concept, and by that I mean that Wrestle Kingdom still tries to be a wrestling show & WrestleMania doesn't just want that. Now I know that WrestleMania is a wrestling show ran by a wrestling company, but it focuses more on the spectacle rather than the wrestling aspect of things. Wrestle Kingdom always focuses on the wrestling and though this could make the matches blend together, but some stick out either way. However, on the WrestleMania side of things there are always matches that stick and they very rarely blend as matches are memorable for different reason. Overall though all companies have their major events, but some look at their special events differently then others and plan further ahead.