Hi Gopi Kumar,

The passing down of traits in the form of genes from parents to their children is called heredity. Every living thing has a DNA master plan that they inherit from their mom and dad.

Variation, in biology, any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences (genotypic variation) or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation).

Hope this will help,please feel free to ask if you have any further queries.

Thank You.

These are the biology terms used in the genetics chapter of biology.

Heredity is referred to the passing of  traits and characteristics through the genes from one generation i.e., parents to the other generation i.e.,offspring.

Variation is important difference because it contributes to evolution of the world and forms on the basis of heredity. Althrough offspring receives all the characters from their parents , they are not exactly the same. The progeny differs in itself and  also with the parents. These differences are called variations.