Dear Student,
Mitosis- The cell division in which one cell (the mother cell or parent cell) divides to produce two new cells (the daughter cells ) that are genetically identical to itself(parent cell). Mitosis has different stages. Mitosis occur in multicellular organism.
Amitosis- Cell division by simple cleavage of the nucleus and division of the cytoplasm without spindle formation or appearance of chromosomes. They lack mitosis. They have only two stages karyokinesis followed by cytokineses. Amitosis occur in unicellular organism as it is a direct cell divison method.
Regards.