A suspension is a heterogeneous mixture in which the solute particles are large enough to settle out of the solution over time. The particles in a suspension are typically larger than 1 micrometer in diameter. Hot chocolate is not a suspension because the cocoa particles are much smaller than 1 micrometer in diameter and do not settle out of the solution.

A colloid is a heterogeneous mixture in which the solute particles are small enough to remain suspended in the solution for a long period of time. The particles in a colloid are typically between 1 nanometer and 1 micrometer in diameter. Hot chocolate is a colloid because the cocoa particles are small enough to remain suspended in the solution.

The main difference between a suspension and a colloid is the size of the solute particles. The particles in a suspension are larger than the particles in a colloid.