Question

Why to use crossover and mutation on genetic algorithm?

Answer 1

mutation and genetic drift are not same. 

A mutation is defined as a heritable change in the genetic material of an organism. DNA sequence of the organism is altered and passed onto the daughter cells as the cell divides.

Genetic drift is the change in the frequency of the alleles of a gene in a given population.

Both of these are important mechanisms for evolution but are totally different.