What is the difference between law and order?

Both are about rules. The difference is between jail and the principal’s office.

Many disordered and chaotic situations are entirely legal.

See my childhood birthday parties. Nothing illegal about them, especially the ones where my dad was supervising, rather than my mom.

There are also many well-ordered behaviors that are extremely illegal.

Having laws does not necessarily mean that they are enforced or that they are obeyed. That is where order comes in.