Is it a toy train set or is a model train set? What is the difference? Both look like small trains, and the difference may appear too subtle for the casual observer. But to train enthusiasts, toy trains differ substantially from model trains. Manufacturers make and market toy trains for children, and many adult train hobbyists will mention that they enjoyed toy train sets when they were kids. Model trains, they will point out, also known as prototyping, constitute a near art form in which adult enthusiasts re-create scale models of real trains and layouts in exquisite detail.