Model railroading hobbyists would be offended if you call their train collection toy trains. For them, it would be like calling a timeless piece of literature a story. Besides, who can blame you? Toy trains and design trains are small in size and are powered by electricity or other kinds of power sources. Nonetheless, you have to look at that there is a distinction in between toy trains and design trains.
Basically, toy trains in the very early days were commonly powered by wind up motors. Some were even powered by heavy steam. In those days, these toy trains were usually composed of cast iron.
Then, electric trains followed. Some were powered by batteries, while there are other toy train sets that were plugged in where the electricity flowed on the tracks to power the train.
Now you can find train layouts in all scales and sizes that will look so lifelike you won’t be able to tell the difference between them and the real thing. When you consider the amount of money, time and effort that goes into setting them up, it’s easy to see why someone would be offended if you called them toys.