All-terrain bike and Mountain bike

All-terrain bike noun - A bicycle with a sturdy frame and fat tires; originally designed for riding in mountainous country.

Mountain bike is a synonym for all-terrain bike in off-road bicycle topic. In some cases you can use "Mountain bike" instead a noun phrase "All-terrain bike", when it comes to topics like all-terrain bicycle.

Mountain bike noun - A bicycle with a sturdy frame and fat tires; originally designed for riding in mountainous country.

All-terrain bike is a synonym for mountain bike in bicycle for rough terrain topic. You can use "All-terrain bike" instead a noun phrase "Mountain bike".