What is exactly the difference between not and no?

Question

Answer

This is a good question because in Spanish the word "no" often does both jobs.

Okay, so:
no = no

Not = a negation, a cancelling out.

For example, 
This is my dog.
That is not my dog.

This is my shirt.
That is not my shirt.

Esta es una buena pregunta porque en español la palabra "no" a menudo hace ambas funciones.

Bueno entonces:
no = no

Not = una negación, una cancelación.

Por ejemplo,
Este es mi perro.
Ese no es mi perro.

Esta es mi camisa.
Esa no es mi camisa.