Updating Prefabs?

I have 2 scenes. First scene contains a button which changes the sprite of a prefab then loads second scene. In second scene I have the prefab object. In Editor, in second scene object is updated with its new sprite but when I build the project, prefab’s not updated. Why built project doesn’t update it? I also tried to Instantiate the same prefab when second scene starts and it came as updated. Previously added object stays same. Do Build system and Editor works different?

You can not change prefabs at runtime.