If you mouseover fighters in the Squadron Management panel, it tells you they are good against LRM and Siege frigates.

A tank might shoot through a truck entirely, but a machine gun would riddle it.
Here are the ships that deal each damage type -- the ships of the damage type being 'targeted'.
Anti-Fighter Frigates -- Fighters,Bombers
DamagePercentBonus:ANTIVERYLIGHT:CapitalShip 0.25
DamagePercentBonus:ANTIVERYLIGHT:VeryLight 1.5
DamagePercentBonus:ANTIVERYLIGHT:Light 1.0
DamagePercentBonus:ANTIVERYLIGHT:Medium 0.25
DamagePercentBonus:ANTIVERYLIGHT:Heavy 0.25
DamagePercentBonus:ANTIVERYLIGHT:VeryHeavy 0.25
Fighters, Colony Frigates, Scouts -- Long Range Frigates, Colony Frigates, Civilians, Siege Frigates
DamagePercentBonus:ANTILIGHT:CapitalShip 0.25
DamagePercentBonus:ANTILIGHT:VeryLight 1.0
DamagePercentBonus:ANTILIGHT:Light 2.0
DamagePercentBonus:ANTILIGHT:Medium 0.25
DamagePercentBonus:ANTILIGHT:Heavy 0.25
DamagePercentBonus:ANTILIGHT:VeryHeavy 0.25
TEC/Vasari Missile Frigates, Sova Missile Platform, Planetary Defenses -- Light Frigates
DamagePercentBonus:ANTIMEDIUM:CapitalShip 0.75
DamagePercentBonus:ANTIMEDIUM:VeryLight 1.0
DamagePercentBonus:ANTIMEDIUM:Light 1.0
DamagePercentBonus:ANTIMEDIUM:Medium 1.5
DamagePercentBonus:ANTIMEDIUM:Heavy 0.75
DamagePercentBonus:ANTIMEDIUM:VeryHeavy 0.75
Light Frigates, Siege Frigates, Utility Cruisers -- Utility Cruisers, Anti Fighter Frigates, Carrier Cruisers
DamagePercentBonus:ANTIHEAVY:CapitalShip 0.5
DamagePercentBonus:ANTIHEAVY:VeryLight 1.0
DamagePercentBonus:ANTIHEAVY:Light 0.75
DamagePercentBonus:ANTIHEAVY:Medium 1.0
DamagePercentBonus:ANTIHEAVY:Heavy 1.25
DamagePercentBonus:ANTIHEAVY:VeryHeavy 0.5
Bombers -- Heavy Cruisers, Planetary Defenses
DamagePercentBonus:ANTIVERYHEAVY:CapitalShip 0.75
DamagePercentBonus:ANTIVERYHEAVY:VeryLight 0.5
DamagePercentBonus:ANTIVERYHEAVY:Light 0.5
DamagePercentBonus:ANTIVERYHEAVY:Medium 0.5
DamagePercentBonus:ANTIVERYHEAVY:Heavy 0.5
DamagePercentBonus:ANTIVERYHEAVY:VeryHeavy 1.0
Heavy Cruisers -- nothing
DamagePercentBonus:COMPOSITE:CapitalShip 0.75
DamagePercentBonus:COMPOSITE:VeryLight 1.0
DamagePercentBonus:COMPOSITE:Light 1.5
DamagePercentBonus:COMPOSITE:Medium 1.0
DamagePercentBonus:COMPOSITE:Heavy 1.25
DamagePercentBonus:COMPOSITE:VeryHeavy 1.0
Capital Ships, Advent Beam Frigates -- Capital Ships
DamagePercentBonus:CAPITALSHIP:CapitalShip 1.0
DamagePercentBonus:CAPITALSHIP:VeryLight 0.25
DamagePercentBonus:CAPITALSHIP:Light 0.75
DamagePercentBonus:CAPITALSHIP:Medium 1.0
DamagePercentBonus:CAPITALSHIP:Heavy 1.0
DamagePercentBonus:CAPITALSHIP:VeryHeavy 1.0
Guess!
DamagePercentBonus:CAPITALABILITY:CapitalShip 0.75
DamagePercentBonus:CAPITALABILITY:VeryLight 1.0
DamagePercentBonus:CAPITALABILITY:Light 1.0
DamagePercentBonus:CAPITALABILITY:Medium 1.0
DamagePercentBonus:CAPITALABILITY:Heavy 1.0
DamagePercentBonus:CAPITALABILITY:VeryHeavy 1.0
These are damage MODIFIERS, mind, base damage varies.