There are two different tools to know the strength of the planet and to make predictions.
In Shadbala you have 6 different bala consolidated into one like Sthana bala, Dig bala, Chesta bala etc. strength due to placement, direction etc of planets. While in Ashkatvarga is how other planets support and oppose a planet. If a planet is strong in both Shadbala and Ashtakvarga it will surely give good results in its Mahadasha and antardasha.