What separates Jose Mourinho, serial winner of trophies all over Europe and widely regarded as the finest manager in the game, and Roberto di Matteo - the former MK Dons and West Brom boss?
One has won the Champions League for Chelsea, and the other has not. And yet, for guiding the Blues to the trophy that owner Roman Abramovich so desperately craved, Di Matteo got the ol' heave-ho just six months later. Mourinho on the other hand, fell out with Abramovich and left Stamford Bridge under a cloud in 2007, but has been welcomed back as a hero. What gives?
The two managers will meet as equals on Tuesday as Chelsea travel to the Veltins-Arena for their Champions League tie, and much of the talk beforehand has been about the impending battle between the pair. Not that Mourinho is particularly happy about that.
"I don't play against him. If I play against him, he wins because he plays better than me," the Special One said. "Unless I am fitter, which I don't know, but normally he wins because he is much better than me. It is Chelsea against Schalke, it is not me against Di Matteo.
Tomorrow's game is an interesting one for Chelsea fans, but not for the angle being spun in the media. Mourinho is right, it's not about him v Di Matteo because frankly, very few Chelsea fans will care that much about the Italian. He'll get a warm round of applause and a few pats on the back, but that's about it. Why is that?
A quick look at the figures say he should be revered; during his short stint in charge in west London he took charge of 42 games, won 24 and lost just nine, winning the FA Cup and of course the Champions League in the process.
His sacking was handled pretty poorly. Even after he guided Chelsea to the Champions League, the former midfielder was handed just a two year contract. Not exactly a ringing endorsement of the faith the club had in him. It was no surprise that he was out the door when things got tough, even though Chelsea had no logical successor lined up and had to opt for Rafa Benitez - not exactly a fan favourite.
Perhaps it's because he doesn't have the profile of his counterpart that Di Matteo was used up and spat out by Chelsea. The cult of personality runs deep in football and the deified Mourinho certainly plays the game better in that respect, but as both a player and a manager Di Matteo has imposed himself on Stamford Bridge over the past couple of decades.
Ultimately, his face just didn't fit the bill. Di Matteo doesn't have the (warranted) reputation of Mourinho, or the ability to work the media like the Special One. And in today's winner-takes-all world of football that's matters a huge deal. He's been given a tough job with a big club but can now move on, starting with a win over Chelsea. If that does happen though, it won't be a big deal. Because, in the pages of Chelsea's history, Di Matteo has become just that guy who helped to win the Champions League.