Next, we create another file named silkworm.py. We will begin by creating a module that performs the same customizations we performed through Developer Mode in Chapter 13, Customizing Odoo for Your Business.
Why would we want to put our customization into a module rather than just using Developer Mode?
First off, changes made through Developer Mode are isolated within that instance of Odoo. If you decide you wish to create a new database, you will have to make all the developer changes by hand, again. More importantly, when you make the changes in a module, you have much more control over the final results.
Developer Mode is very powerful for quickly looking at views, analyzing fields on forms, and understanding more about the Odoo framework. However, it is typically far better to make any actual changes by creating a module rather than modifying the views or models in Developer Mode. So unless you are using Odoo Online it's better to avoid changes in Developer Mode.