Hello friend;

 Here is the difference between the different terms.

APP:

App is an abbreviated form of the word "application." An application is a software program that's designed to perform a specific function directly for the user or, in some cases, for another application program.Which means that an app can contain many modules.

Ex: Odoo VoIP, Amazon-Odoo Connector...

ADDON:

The addons folder it is not supposed to be the one inside server. At the same level as server there's probably a folder named addons. we place our modules there.

Ex: hr: which is a module that contains configuration of department, employee, contract...

MODULE:

Some code developed to realise some thing and will be placed under /Addons to be a part of APP.

PS: - An App can contain many modules but in the same folder under addons as we can create many modules each one in a folder but under the Addons.

So that, in structure App is the purpose of modules which are defined under /Addons.

Best Regards.

I wouldn't know any difference, why does it matter? 😉

in OpenERP you can add custom modules to any "addon" directory you'd like; just make sure you have it in the path (as defined in your configuration file generally).