This question already has an answer here:
- How can I compare guns in BF3? 1 answer
How do these 3 sniping rifles compare in accuracy, damage, reloading speed, bulletdrop, rounds per magazine,...?
All are bolt-action sniper rifles. The M98b does a higher damage-per-shot rate but has a much smaller magazine and longer reload time.
All info from the Battlefield 3 Wiki. Symthic.com has a excellent comparison tool for looking at different weapons.