thx for the info.
is there a chance to hit both inside and outside VATS?
When you use freehand aiming, your accuracy is partly determined by how well you aim, and the rest is partly random chance of where inside your projectile's possible 'cone of travel' a given bullet or energy pulse happens to get put in by the game's dice-cup when it's fired. A lot of factors affect this part, from what gun you are using, what mods it may have, what perks you use, whether you are moving, standing or crouching when you fire, how far away your target is, and so forth. But there are some weapons with a very narrow cone of 'spread' for their projectiles, and those are very close to being a hitscan weapon (virtually 'hit exactly where you aim', even at long distances). With those weapons, if you are a good shot, you'll be a stone killer. For a reference on all weapons in NV and their individual specifics, I use this site:
http://fallout.wikia.com/wiki/Portal:Fallout:_New_Vegas
Search under Items > Guns.
Usually, it will be a lot easier to pick out and hit specific body parts in VATS, than it is freehand. But a lot depends on your distance from the target, and what VATS-enhancing perks you may have chosen- ones like Commando, Gunslinger, Sniper, etc. At medium to shorter ranges, and with good VATS +hit% bonuses from perks, you can be very deadly at choosing specific body parts to disable and kill your opponents. At longer ranges, VATS isn't so good. If you are freehand-aiming and not using VATS, you can sometimes get one well-aimed shot off at a specific bodypart from Stealth or hiding, but after they start running around and charging you over uneven terrain and around misc. objects... heh, you're often lucky just to hit them anywhere on their body freehand, forget specific bodyparts.
I'll usually go for sneak kills with freehand headshots (as already mentioned, headshots are the best kill-shot in the game, if you can make one), and then finish off with VATS at closer ranges if that doesn't kill them or if they have friends. Once you end up with multiple enemies closing in on you at close range, VATS is your best bet to survive- well, unless you are an uber-FPS shooter god who never misses in wild close-in furballs. I'm not.