A hill is a smaller, gentler rise in the land, while a mountain is much taller and steeper. If you can stroll up it without much effort, it is probably a hill; if it takes serious climbing, it is a mountain.
The core difference
A mountain is a much taller and steeper landform than a hill.
- hill — a raised area of land, smaller and less steep than a mountain: the village sits at the foot of a gentle hill.
- mountain — a very tall, steep natural landform rising well above the surrounding land: they spent the weekend hiking in the mountains.
How to tell them apart
There is no strict cut-off point between the two, but the difference is one of scale. A hill is a modest rise you can walk up in a few minutes; a mountain is a dramatic, steep landform that often needs proper climbing gear or a long trek to reach the top.
Both words are also used loosely beyond geography. A sloping section of road can be called a hill, as in a truck struggling to climb a steep hill, and gardeners even use "hill" as a verb, meaning to pile soil around a plant. "Mountain" gets the same figurative treatment for sheer quantity, as in a mountain of paperwork.
