Run the evaluatable cells in a notebook file:

• Only evaluatable cells are evaluated (usually only Input cells). Unevaluatable cells such as text and outputs are not evaluated.
• Cells are evaluated in order, whether or not they are initialization cells. Some evaluations may fail if they depend on the initialization cells being evaluated first.

Run the initialization cells in a notebook file, then all evaluatable cells. Initialization cells are evaluated twice (which is usually ok):

• Only evaluatable cells are evaluated (usually only Input cells). Unevaluatable cells such as text and outputs are not evaluated.