There is a difference between עפר (dirt) and אדמה (earth) with respect to detachment from the earth: It will say the nounאדמה when talking about a clods of earth attached together as a whole, while the noun עפר is about the morsel and the eroded. In its precise meaning, it means only the dirt of the ground, and in its broad meaning, it also includes crushed stones, bricks, and clay.