Bolt Actions Speak Louder Than Words
Sniper Rifles belong to the Small Guns category and have the highest range in the game, only surpassed by Big Gun Snipers which are special rare weapons. What separates Sniper Rifles from Assault rifles is that they do not have selective fire capabilities, meaning they can not fire bursts. All small gun snipers apply bleed damage, often have their view range extended through the scoped weapon trait and also are much slower to fire, both in terms of AP cost and animation time.
As a rule of thumb, long range results in lower damage and vice versa. While the game itself makes no distinction, the sniper rifles could be separated into two groups, slow firing, long range sniper rifles on one hand and designated marksman rifles or DMR's on the other, usually in the form of scoped assault rifles with a higher rate of fire and higher DPS, but less bleed and range.
In order to get the most out of a sniper rifle, it is important to take one's character build into account and the type of battlefield that will be fought on. With high small guns skill and all weapon perks unlocked, all snipers synergize differently.