A regular condition is the value of an entity specified in the VRF scope, or a simple comparison with the value - is greater than, is less than, is greater than or equal to, is less than or equal to.
A custom condition can use the rule language, standard functions, and data in the scope of the function at runtime (for example, scorecards and global variables). It can contain complex formulas.
A regular action sets the value of an entity specified in the VRF scope.
A custom action can use the rule language, standard functions, and data in the scope of the function at runtime to do whatever is desired. For example, the action could be to send an event out to a different system for follow-up.