difference between molecularity and order of a reaction

The Major difference between molecularity and order of a reaction is that Molecularity is the number of atoms, ions or molecules that must collide with one another simultaneously and result in a chemical reaction while the order of a reaction is the sum of the concentrations on which the rate of reaction actually depends.

Order of Reaction

1. It is the sum of all the exponents of the concentration of reactants involved in rate equation.
2. Its value can be in whole number or fraction.
3. Its value can never be more than three.
4. It can be zero.

Molecularity of Reaction

1. It is the total number of atoms, molecules or ions present in a single step.
2. It’s value always in the whole number.
3. Its value can be more than three.
4. It can never be zero.