The relationship between rocks and stones is pretty clear. Rocks are composed of smaller stones, while are stones are obtained from rocks. Let's consider their formation. Rocks are of different types i.e., igneous, sedimentary, and metamorphic rocks. The mode of formation of one of these types is by the eruption, cooling, and solidification of molten magma.
On the other hand, weathering is an important process in the formation of stones. In terms of size, stones are not as big as rocks. As you would expect, stones are not as heavy as rocks. While rocks are in different sizes, most of them are immovable, whereas stones are movable unless they are in the soil.
Unlike stones that are used as materials during construction, rocks are not always used for this purpose unless they are broken down to stones. There are hard rocks as well as soft rocks, but stones are generally hard materials.