Confusing to have two kinds of motions

Here is one Elkins Task Force recommendation:

Simplify forms for motions. In family law cases there are currently before the court: a notice of motion and an order to show cause. almost interchangeably. In other counties, they are used for distinct intended differences are not written and may not be accessible attorneys who do not regularly practice in the county. [p.49]

I must admit, I have brought both kinds of motions, and I have had both kinds of motions brought against me, but I have never figured out the difference. They have slightly different forms and service procedures, but they all get heard together and they seem interchangeable to me.