Motorized bicycle is used as a term once in the code, but that is in relation to taxation, which only applies to the lone article.
Moped is derived from MOtor and PEDal. It's the same thing, the difference being that in the 60s and 70s they were really up and coming, and those bikes were 140 something CC. Idaho never officially recognized Motor-Assisted Bicycles (which is the new term in many states), so there is a lot of crossover in the laws, as they once applied to an essentially different vehicle.
But, we take what we can, and we adapt to the laws beset before us with the materials we have access to.
Idaho's current laws are actually really awesome in how they apply to motor assisted bicycles - most states that do recognize them and pass legislation over them end up making you register, insure, M endorsement, the whole nine yards.
It's not so much that there needs to be renditions to the code in place currently, it's that the right amount of research needs to go into it so that we know we are in compliance with what exists. The more I look into it, the more I find bicycle laws and moped laws MORE than forgiving to anyone riding in Idaho.