New to Community and AEM 🙂 and this feels like 101 question, but have read up an searched but did not find any real info on Project Benefit of using it. (I did find info on how to create, issue etc.)
Our current structure we have numerous sites. Each sites was create by creating a page and then building from there. One of the main issues is that all users can see all the sites, etc so there is risk that marketing person can accidentally change another brand's site. I was wondering if this was something we can solve with Project.
Therefore what is the benefit of creating a site within a Project instead of creating from a page.
As @BrianKasingli and @ArpitVarshney mentioned, the primary way to solve your problem is to provide correct access restrictions to the users . You have to create correct set of groups for your content authors/ managers and set permissions for them to the correct set of pages so that they won't be able to access the pages which they are not intended to. Rest of how to create groups and manage the same are mentioned in the above answers.
When you create the project and add users to the various roles, groups associated with the project are automatically created to manage associated permissions. For example, a project called Myproject would have three groups Myproject Owners , Myproject Editors , Myproject Observers . However, if the project is deleted, those groups are not automatically deleted. An administrator needs to manually delete the groups in Tools > Security > Groups.