First of I'll start by easing you into the world of sniping by going over the two sniper rifles avaiable in Crysis 2.
The DSG-1
The DSG-1 is the first sniper rifle you unlock - and will probably use for most of the game untill level 39.
The DSG-1 is a semi-automatic sniper rifle, that requires to be cocked when last round has been shot out of the magazine - this is quite important - you should try to keep a bullet in the chamber before reloading to considerably reduce reload speed! Remember that the longer you spend reloading the more kills you miss and are more vounrable! DSG-1's fire rate is almost twice greater than the one of the M2014 Gauss Mk. 2 - this means even if the first shot isn't a killshot you can usually fire off another one to kill the enemy before they have any sort of idea what is happening - BIG UP! Another great feature of the DSG-1 is the ability for it to have a silencer. From my experience the DSG-1 with silencer is exacly the same as it's unsilenced equivalent with the exception that DSG-1 silenced offers a much stealthier class - again, BIG UP!
DSG-1 Setup:
http://s184.photobucket.com/albums/x139/Mdusiek/?action=view¤t=2011-03-31_00004.jpg
Armour module - it is absolutely up to you! Armour is not the ability you are going to utilise
Stealth module - Visor enchance THE ABSOLUTE MUST HAVE! enemies are highlighted RED! This help out tremedously if you do not use it you are hindering you're sniping skill
Power module - Retriver this is perhaps the most usefull module for the sniper, perhaps even more than the visor upgrade as you will not have to leave your nest in order to get the dogtags - retriver II - 1 less dogtag for killstreak - retriver III longer killstreaks!
The M2014 Gauss Mk.2
The M2014 Gauss Mk.2 is the "big daddy" of the sniper family, unlock at a whooping level 39. It packs a considerably greater punch than the DSG-1. This power comes however at a price - the fire rate is much much slower - make your shots COUNT!
Another thing to remember the Gauss is not able to be fitted with a silencer - and it makes ALOT of noise!
Apart from the big bang it also leaves a very clear blue-white smoke trailing to your spot - again this is to hinder your stealth gameplay! The only real advantage that the Gauss has over it's weaker opponent is the AWSOME stopping power! You will be able to kill enemies through objects with much greater ease.
http://s184.photobucket.com/albums/x139/Mdusiek/?action=view¤t=2011-03-31_00004.jpg#!oZZ4QQcurrentZZhttp%3A%2F%2Fs184.photobucket.com%2Falbums%2Fx139%2FMdusiek%2F%3Faction%3Dview%26current%3D2011-03-31_00007.jpg
Same setup as the DSG-1, jsut showing the attachments i use

Now for damage charts and more direct statistical comparison.
First of all i would like to say that the below information is from Den Kirson's website found at http://denkirson.xanga.com/742784256/crysis-2/ all credit from weapon stats goes to him and not me!
Weapon Damage charts from DenKirson!
The Player has 100 Health.
The Nanosuit has 100 Energy.
Armor drains 2 to 7 points of energy per second depending on the player's movement speed. His movement speed is also decreased to 80%.
Armor absorbs a percentage of damage to the Player's health. 35% of the damage is diverted to his Suit Energy.
If for example, a player with Armor is hit in the torso for 30 damage. His health takes 19 damage.

http://s184.photobucket.com/albums/x139/Mdusiek/?action=view¤t=dsg1.jpg
I hope you guys enjoyed this guide and that it helped. I might include some gameplay with both snipers to show what the difference is!
Remember - aim high!
*PHOTOBUCKET LINKS DONT WORK :@*