Authorisations, unlike SCIAs, are the applications submitted by entrepreneurs to the Public Administration to engage in specific business activities associated with the production of goods or services, or to perform work relevant to their business operations. And, unlike SCIA notifications, to perform work or commence the activity, you must wait for the SUAP's positive response (official approval).
Authorisation is required only when expressly provided for by the laws governing specific sectors of productive activities or services (e.g. trade in public areas, industries with harmful emissions or discharges, medium and large retail facilities, catering activities located in areas subject to territorial planning, etc.).