We all know that CityVille is big (100 million users big). But, how do Facebook games stack up against the heavyweights in the core video game space, such as Activision’s Call of Duty: Black Ops?

I’ve often pondered this question, as have the fine folks at IGN who put together a chart comparing the top games on Facebook and in the retail video game space in 2010 by revenues and users.

Not surprisingly, the most popular and top grossing game of 2010 was Activision’s Call of Duty: Black Ops. Interesting, 4 of the top 10 games of 2010 in terms of size and revenues are social games on Facebook and all 4 are by Zynga.

Halo Reach, Red Dead Redemption, Super Mario Brothers (Wii), Madden 11 and WiiFit Plus are in the top 10 list, but all under Zynga’s CityVille and FarmVille.

Though Call of Duty is the #1 game, this is not necessarily good news for the video game guys. Activision spent a lot more money on game development and marketing than Zynga for CityVille. And, because the video game space is a more hit-driven business (like movies, the sales happen at launch) and social games are more about the tail, CityVille has a lot more long-term revenue potential.

You can go to IGN for the full article and pretty Top 10 chart. There is no doubt, while video games makes the most money, the trend is definitely with social games.