Emergency v Crisis

What is the difference between an emergency, and a crisis?
A flood is an emergency. It happens fast, and demands that we react now.
Building flood defences in the face of rising sea levels is a crisis. It’s slower, and requires a planned response.
Much of our current predicament is both an emergency and a crisis. There are things we need to do now - and things we need to consider more carefully. At what point do we fix that dripping tap? At what point does building sea defences to mitigate flooding shift from being a crisis to an emergency?
Even when we understand the distinction between emergency and crisis, it can still be hard to tell the difference. And when we dither, then a crisis can become an emergency.
These are complex ideas, and there aren’t simple solutions.
But perhaps they are worth thinking about?