Dosha relates to our physiology - but our physiology changes over time. So in Ayurveda we use two dosha readings - one to determine our true nature, the other to indicate any imbalances.
Prakriti refers to our true dosha. It is, if you like, our true physiology or nature, the way we were born, unchanged by time, aging or illness.
Vikriti however refers more to how we are now, incorporating any imbalances and changes that may have occurred over time.
When Prakriti and Vikriti are the same this indicates good health.
Ideally you will take the test twice to determine both Prakriti and Vikriti. Tip: for Prakriti try to recall how you’ve always been, especially your nature as a child. Vikriti answers should be based on how you are now.