I have been a player since the beta stages of Chernarus Life which was around the ARMA2 international release. I've been a beta tester for City Life RPG for a few months now.
The difference between City Life and Chernarus Life is the ambience and flow of life through the game. Since City Life has an addon pack (Fairly large albeit) there are many items that you would come to expect in an RPG now available in ARMA2. It just adds to the feeling, that you are somebody, trying to make it on your own.
Everything is pretty much droppable, you can get mugged, do drugs, go to work, and cause chaos. It's a perfect mix of crazy in some senses.
In terms of the chaos, it will inevitably be the same in some regards, but the tools are available to combat most crime in City Life, including the tasers. In City Life, there's so much to do... last time I got drunk and died from alcohol poisoning! The cops followed me because I was drunk, so I pulled over and was busted for using a kickbox animation.
These guys are absolutely dedicated to their game, and constantly develop it, tweaking things, adding features, making things more balanced, and do not rush their product like Chernarus Life was originally.
To be fair though, Chernarus Life could get an addon pack, as I've heard so, and after many fixes it too is fairly stable, so long as it doesn't have a lot of people on, and so long as the server hasn't been up more than 48 hours. Nonetheless, I would say I prefer City Life because of the game balance and items, the custom cars, and the developers themselves. I've worked with the author of Chernarus Life, and he's not that bad of a guy, but he is just one guy, so there's only so much he can do.
The other Chernarus Life servers which ripped him off are up, and have added some features, but the feeling for them is the same across the board, stock ARMA2 gets old after a while. Chernarus Life does have an edge in factory manufacturing still, and I did like their GM console for sponsoring non-RP events to keep players interested.