* Differentiation: This is the process where a cell changes from a general, immature state (like a stem cell) to a more specialized one. It gains specific features and functions, like becoming a muscle cell, a nerve cell, or a red blood cell.

* Development: This is a broader term encompassing the entire process of growth and maturation of an organism from a fertilized egg. Differentiation is a crucial part of development, but not the only one.

Think of it like this:

* Development is like building a whole house, involving many steps.

* Differentiation is like building a specific room in that house, like a bedroom or a kitchen.

So, differentiation is a key part of development, but not the whole process.