Dead Butterfly

When is a butterfly a dead butterfly? A dead butterfly does not look, at least initially, any differently from a live butterfly. There are people who have mottephobia, the fear of butterflies, whether dead or alive. There is, of course, a real difference between life and death. Yet it is not easy to pin point what it is, and it is impossible to put that something back once it is taken away. Why is that?

When someone dies, is the life transformed into some other form of existence? Or the life simply extinguishes? Or is it wrong to think of individual lives, that in fact all lives are connected as a whole, hence one never dies but simply returns to the whole?