Why does Egypt's kings have different crowns for different things?

Answer 1

The red crown, the chair shaped one with a sort of curlicue on the front (probably a stylized cobra, the symbol of the goddess Wadjet ) was the traditional crown of lower Egypt, the part of Egypt containing the delta where the Nile empties into the Mediterranean Sea. The tall white crown with the bulbous top is the traditional regional crown of upper Egypt. When Egypt was unified under one pharaoh then that pharaoh would often be depicted as wearing both crowns at once. The cobra or uraeus often seen on the front of a crown, usually with a vulture head, the symbol of Nekhbet, a goddess of upper Egypt.

Each crown was worn separately to show sovereignty over the particular part of Egypt. They were worn together to show the unification.

There are two other headdresses often seen on depictions of the Pharaoh. One is a piece of cloth with a uraeus and vulture on the front. The other is the "blue crown" or war crown. The cloth was probably more comfortable than either crown separately or together given the climate. The war crown was probably to provide protection to the Pharaoh when he was acting as a war leader.