well, ARMA is hands down king of realistic infantry simulator, though I didn't play much as RO as arma requires much more time, tactics, communication..
One thing I can sure of is that RO1's battle feels more similar to ARMA2 project reality. harsh, tough, rough, very hard to kill bunch of enemies in short time with my noobish skills.
However, RO2 is more easy to move, aim, pinpoint shoot that almost feel like arcade shooter, and I can kill many opfors if I only act careful enough. much easier to kill opfors and much easier than ARMA2 PR's cqc.
Both are focused on PVP CQC.
Also not sure soldiers can run and gun so effectively all the time just like RO2. so it feels more arcadic than ARMA2 PR.
TBH, RO1 has more harsh, brutal atmosphere though old graphic might not suit everyone's taste in 2011.
RO2 looks shinier, but has somewhat muzzled sound design and somewhat arcadic feel to it.
Both are good CQC PVP game though.
RO1 has big tank maps..
RO1 had EAX support and working sound system that supports dedi sound card.
RO1's gun/ explosive sound sample were somewhat crude and raw but it's not modified like RO2's and relatively well preserved in loudness and echoing effect.
1. Ro2's gun sound has low decibel level, rarely echoing
2. Ro2's gun sound is somewhat muzzled like BF3's gun sound, and I don't like those muzzled modified gun sound.
3. Ro1 (ARMA1,2, insurgency mod) has cracking (thump) bullet sound when a bullet passes by players, and this gives more immersion and pseudo realsitic sentiment of being in battlefield full of flying lead. RO2 doesn't have this.
Real guns sound really loud and have harsh cracking mechanical sound, not somewhat muzzled sound like BF3 or RO2.
and real life explosive can blow your ear drum in some cases, but games can't have these therefore most arcadic FPS dev's muzzle the gun/ explosive sound to protect gamer's ears.
ARMA, RO1, insurgency kind of games have less modified sound and they don't sound muzzled.
Though RO1's sound might not be entirely correct but they are closer to real thing.
Comparison vids.
mp40 - YouTube
Mauser K98 - Fast shooting - 5 shots in 4 seconds - YouTube[/URL]
ro2
Red Orchestra 2: Heroes of Stalingrad - K98 Madness - YouTube[/URL]
ro1
Red Orchestra: K98K target shooting - YouTube[/URL]
Wish modders can revive this unmuzzled harsh cracking gun/ explosive sound.