There really is no comparison. Arma 2 is the true successor to the OFP legacy.
OFP2

R is truly pathetic. It must be an incredible experience on the Xbox being as they don't have many large scale combat games like this, but when Codemasters says "This is the most realistic game you will ever play" they have obviously been smoking crack because their idea of realism is way off.
Nations around the globe use a form of Arma to train their troops with, and it receives much praise from those who use it. If OFP2 were used to train any army, it would have about as much chance in a war as an army of lollipop ladies battling the Mongolian horde.
If this weren't titled Operation Flashpoint, this might have been a perfectly entertaining, if rather limited and dull, game. However because it claims to be both realistic and a continuation of a much loved war simulation game, they have failed so miserably it pains me to admit I have it sitting on my desk.
Off with the gloves, I don't know what the fuck Codemasters was thinking. I think what happened was they had some retarded moron who ran an OFP fansite "guiding" them on how the fans would like the second game to be. If this is the case that fat twat has not only borked what could have been a fantastic title, he has also murdered his chances of continuing a career in the games industry.
It sort of reminds me of when Homer's long lost brother asked him to design a car to break his company out of a rut.