No, loam and topsoil are not the same. While loam is a category of topsoil, not every topsoil is loam. Loamy soils have a composite of sand (less than 52 %), silt (28 – 50%), and clay particles (8 – 28 %). Topsoil, generally, refers to the uppermost layer of soil in a yard or garden regardless of the amount of sand, silt, or clay that it contains.