During cell differentiation, unspecialized cells mature into and evolve to perform a specific function.
This also occurs due to differential gene expression, changes in their shape, cell wall, protoplasm, etc.
For example, a cell loses its protoplasm and develops a lignified cell wall to facilitate the transport of water by the tracheary elements of the xylem.
A single-cell zygote also gives rise to multicellular plants and animals by the process of differentiation.
Totipotent cells can then differentiate into any kind of the cell, e.g. blastomere, whereas pluripotent cells can also give rise to many different types of cells, e.g. the stem cells of bone marrow.