Assumption and Instinct are different from one another.
Assumption is when you assume something that could possibly happen. Or thinking in advance solution for some other things, like possible outcomes of some sort of things.
On the other hand, instinct is the feeling that you didn’t assume to happen, but it suddenly happened, you suddenly feel that something is happening or there is something in you that you cannot explain. But like the assumption, these things might not true or might not happen.
Just like what i wrote, these are my assumptions on how this things differ. haha