Gauss cannons are very short range low damage very high rate of fire. They can be modified for lower accuracy and size to fit into fighters, or turrets.
Lasers are long range beam weapons with damage that drops off with range. But high damage at close range.
Railguns shoot four projectiles at once and their total damage is approximately one third higher than a laser of similar technology. They also drop off at range like lasers, and because the damage is spread over 4 projectiles they don't have the same individual punch, but they can make up for it with greater total damage.
Particle beams are a fixed damage weapon and therefore cause the same damage across their entire range. Although not quite a long-ranged as lasers, athey will out-damage lasers at maximum range.
Meson Cannon inflict only one point of damage and have half the range of an equivalent laser, but the damage ignores shields and armor.
The Plasma Carronade is a high damage, point blank range weapon, The calibers available are larger than those other beam weapons at a similar tech level so this is usually the weapon with the highest damage at close range. It cannot be turret mounted and is far from ideal as a point defence weapon.
The High Power Microwave is similar to the meson cannon, in that it causes only a single point of damage, has similar range, and goes through armour. However the HPM is affected by shields and does triple damage to them. Once the shields are down, the HPM damages ,sensors, fire control systems, ECM and ECCM. The HPM is designed to blind an enemy rather than destroy him.
