Understanding Doctrine of Basic Structure aur Basic Features

Meri aapko pata hai ki hamara Constitution ka ek bahut hi vishesh aur mahatvapurn hissa hai Doctrine of Basic Structure. Lekin yeh basic features kya hai? Dono mein kya fark hai exactly? Koi meri madad karein.

Abhi mere saamne ek doubt hai ki agar ek kanoon ya rule Constitution ke against hai toh aapko use invalid karna chahiye ya nahi? Kyonki agar aap use valid karna chahiye toh yeh Basic Features ka hi hoga ya Basic Structure ka? Aur agar aap use invalid karna chahiye toh aapko Basic Structure ka hi khayal rakhna chahiye ya Basic Features ka? Toh dono mein kya difference hai?