Difference between Doctrine of Necessity and State of Emergency: yaar kya hai ye confusion?

I'm so lost, please help! I've been reading about these two concepts in class and I just can't distinguish between them. Both are related to extraordinary situations, but what's the difference? In the Kesavananda Bharati case, the doctrine of necessity was applied to justify the 24th Amendment, but then I read about Article 359 and how a state of emergency is declared. It seems like both allow the government to bypass certain provisions, but I don't get how they're different. Please explain it to me like I'm a 5-year-old. I'm really struggling to understand the distinction. Help me out, guys!