Growth refers to the constant increase in size, but it should be irreversible like the development of a plant from a seed. Now, this development is not reversible. So it can be said that it is growth. But if a cell swells in a hypotonic solution, then it cannot be considered as growth because it will shrink when kept in a hypertonic solution. Growth is a permanent increase in size and dry mass, by an increase in cell number or cell size or both. Growth involves an irreversible increase in the dry mass of an organism. Dry mass is a more reliable measure of mass than fresh mass because, in dry mass, there is no wet mass which is not permanent.

Development implies a change in shape, form or structure resulting in improved working or in functioning. It continues after birth till death. It is influenced by both heredity and environmental factors. Growth and development take place simultaneously, but they are different. They are inseparable although different. Development is the increase in complexity of an organism as it grows. Development refers to the change in the structure of a body which results in a change in functions.