The process by which unspecialized cells become specialized cells is called

The process by which unspecialized cells become specialized cells is called differentiation or cellular differentiation.

Explanation:

The stem cells or the pluripotent cells are capable of giving rise to all cells present in the body of an organism. In the embryonic life, the stem cells are divided further into different cells. These cells are initially unspecialized, later, they become specialized to form a specific cell or tissue, this specialization of the cell is referred as differentiation or cellular differentiation.