SharePoint: Do I need a page or a subsite?
Q. When should I create a page, and when should I create a subsite?
A. Some SharePoint Farm Administrators or Top Site Administrators choose to make their lives easier by not permitting Subsite Administrators to create further subsites. This leaves only the creation of new pages as a means to present different sets of content for different end uses. Other environments have become a crazed hierarchy of subsites, sub-subsites and sub-sub subsites. What is the right answer? 
If the same people will be using all or most of the sub-subsites, then you really need pages. If the content and permissions differ significantly, then a subsite is probably called for. A page is just a different “window” on the same collection of content. For example, if you are the Site Administrator for Human Resources and you have a small team that performs both traditional HR duties and payroll duties, pages are a good answer. You could create a payroll page with lists, libraries and other content that support that function and an HR page with that content. With carefully structured permissions, you could even create an “employee” page with access to employee resources.
Conversely, if you have a large HR department, where the functions are separate, and there is a greater barrier between employee resources and team resources, then the highest level subsite could be the employee site, with stricter access on the two sub-subsites, one for HR and one for Payroll.
