The particles in a colloid are larger than those found in a solution. The sizes of the particles in a colloid range from 10^-8 to 10^-6 meters, while a solution is made up of ions, atoms or molecules, which are 10^-9 meters or smaller in diameter.
Both colloids and solutions are homogeneous, meaning that their compositions are the same throughout. However, a solution is clear and transparent, while a colloid is cloudy. The two can be differentiated by using the Tyndall effect. This is done by letting light pass through the sample. When the sample is a solution, the beam of light is not visible, but when the sample is a colloid, the larger particles will reflect the light and make it visible.