The purpose of direct damage ships is to destroy the enemy ships as fast as possible. Most of the time this means Battleships, Battlecruisers or HACs. There are also a couple philosophies ships in this role can have:
Totally tooled for damage. All damage/tracking mods in the lows, tracking/sensor enhancements in the mids. This setup can do a lot of damage, but will die very fast to enemy fire. Not a problem if you're not attacked, though.
Hardeners and armor repairers or shield boosters fitted in mid slots or low slots. This ship can take a lot of damage, but its damage output is lower. Battlecruisers and sniping HACs will generally fit for all gank while battleships will use damage controls and shield extenders/armor plates to increase effective hit points.
This is the most common type flown for fleets. While the damage output may seem low, when the fleet is large and everyone is shooting at the same target - the damage adds up quickly.
Snipers can deal good damage beyond 130km with turret weapons. Firing missiles that can hit beyond 100km will not get you the title of “sniper” because enemies can see that they have been targeted by a missile ship and warp away and back, causing the missiles to miss their targets, and friendly turret fire will often obliterate the target before your missiles are halfway there. Snipers with T2 Guns can hit well above 200km, but are usually encouraged to have optimal around 150km and more tank. Battlecruisers and sniping HACs will often have optimal lower than battleships, near 100km, but are much more effective at hitting small targets such as frigates and interdictors.
A Battleship, Battlecruiser or Cruiser that is fitted only to do damage at close ranges, between 5km and 30km. Such ships fit autocannons, blasters, pulse lasers, or occasionally missiles. A ship fit for close range can do much more damage than its sniping counterpart, but the damage increase comes at a cost. Close range ships primarily have to worry about closing the gap between them and their targets before they are destroyed or the enemy escapes by warping away. Close range ships (especially close range Battleships) also have to worry about tracking their enemies. Many close range ships utilize on neutralizers to drain energy from enemies and drones to augment their damage dealing capabilities.