Natural resistances
Every ship has a number of natural (unfitted) resistances to shield and armor damage. Tech I ships from the same faction have the same natural resistances, but this rule does not apply to Tech II ships.
Hull Resistances
All ships have natural 33% hull resistance.
Shield Resistances
T1 ships generally have the same natural shield resistances: 0%/20%/40%/50% (EM/Thermal/Kinetic/Explosive - this order will be used throughout the section).
Some Special Edition T1 ships have a different shield resistance profile. For example, ships from the Society of Conscious Thought generally have a 27.5/27.5/27.5/27.5 (even) profile, although the Apotheosis shuttle has the regular 0/20/40/50.
Ships with skill-based shield resistance bonuses
Some Caldari ships and all Guristas ships (except the titan) have a bonus to their shield resistances. The bonus resistance is 4% for each level of the pilot's (Caldari) ship skill.
The Caldari ships with this bonus are the Merlin, Moa, Drake, Rokh, the Phoenix and the carriers.
Tech I
All Tech I ships of a particular faction have the same natural resistances, be it a frigate or a titan.