Hi,
In my understanding (and quoting a knowledgeable/elevated soul) Karma is broadly classified into Sanchita (accrued from past karmas), Prarabda (Part of sanchita allocated for the current birth), Kriyamana (currently being performed) and Aagami (future actions ). All actions under Kriyamana and Aagami get added to Sanchita after actions and karma is created.
The Jataka or birth-chart/horoscope is basically a representation of Prarabda at the time of birth but may also contain some hints of Sanchita. It is said that all Kriyamana and Aagami karmas contain an element of Freewill though prarabda can also influence the same. Their relative strengths depend on the strengths and influences on Lagna Lord, House / Lord of the house concerned, Moon/Chandra etc.
Prarabda karmas are further divided into Dhrida, Adhrida and Dhridadhrida. It is said that effects of Dhrida Karmas can’t be avoided. In other cases, simple or complicated remedial measures can perhaps alter the Karma result positively or the freewill can alter it either way.
Kriyamana karmas merge into Sanchita karmas as earlier said. The result of some of these can be experienced even in the current birth while others may be carried over to the next births. This may result in altering the nature of Adhrida and Dhridadhrida Karmas in the current birth. While Dhrida karmas can’t be avoided, the extent of their results can also be marginally changed by the current life actions if they fructify in the current life itself.
Destiny is another name for Prarabda. But actions and Destiny go hand in hand. Each is useless without the other. Only in case of Dhrida Karmas, one is propelled to do the necessary actions by the invisible hand.
Hopefully, this will help you understand the basic concepts of Karma, as also address your query.
Take care…