An ability is something a creature can do. The evasion ability allows a creature to take no damage when certain Reflex saving throws are successful. Abilities may be prerequisites for other abilities or game objects, and may have prerequisites (you cannot gain improved evasion if you do not have evasion).
A feature is an aspect of another object that grants an ability. The first edition rogue class has an ‘evasion feature’ that grants the ‘evasion ability’. A feature is unlikely to have prerequisites because they are not ‘chosen’ or ‘selectable’ by the player. A feature will never be a prerequisite for an ability or other game object. When a ‘feature’ depends on another one (evasion and improved evasion, uncanny dodge and improved uncanny dodge) the prerequisites are actually on the underlying ability. A feature may place restrictions on when the ability can be used.
An option allows a player to choose (make a choice) of ability. Rogue talents, rage powers, and domains are all options, and the player can choose one when granted (as by a feature).
Interactions and Examples
An option may have features.
- The rogue class has the evasion feature and the rogue talent feature.
- The battle mystery has the revelations and final revelation features.
A feature may grant abilities and/or choices.
- The evasion class feature grants the evasion ability.
- The rogue talent feature grants the player a choice of rogue talent options.
- The revelations feature grants the player a choice of revelation options.
- The final revelation feature grants several abilities (each mystery grants different abilities and the player has no choice).
These are broad classes defining how the different aspects are gained or applied to a creature. In practice I expect to refer to them by their actual name (‘improved evasion advanced rogue talent’), but behind the scenes their classification will define the rules behind their selection.