The absolute growth rate is the measurement and the comparison of total growth per unit time, while the relative growth rate is the growth of the given system per unit time which is expressed on a common basis
Arithmetic growth:
In arithmetic growth, one of the daughter cells continues to divide, while the other differentiates into maturity. The elongation of roots at a constant rate is an example of arithmetic growth.
Geometric growth:
Geometric growth is characterised by a slow growth in the initial stages and a rapid growth during the later stages. The daughter cells derived from mitosis retain the ability to divide, but slow down because of a limited nutrient supply.