In Hinduism, the principle that governs the circumstances of one's future life is karma. Karma refers to the law of cause and effect, where an individual's actions (good or bad) have consequences that can affect their future lives. Positive actions lead to positive outcomes, while negative actions lead to negative consequences, influencing the nature of one's reincarnation.
Reincarnation, or samsara, is the cycle of birth, death, and rebirth that souls undergo based on their karmic actions. Moksha, on the other hand, is the ultimate goal of liberation from this cycle, where the soul attains union with the divine or the ultimate reality, thus escaping the cycle of samsara.
In summary, karma influences one's future life circumstances in the cycle of reincarnation, while moksha represents the ultimate release from that cycle.