Generic resource are used for role-based placeholders and for planning. If you are perform top-down planning you would use generic resources. The most common use for generic resources is in your project schedule templates and looking at Resource Availability by Role.
Local resources are not able to access your project information; they can not utilize time tracking through Project Web Access; and you are not able to report on local resources.
Project Online is our new online project and portfolio management (PPM) service delivered through Office 365 and Project Server 2013 is our on -premise project and portfolio management (PPM) product.
This is a common question for those looking to implement Microsoft Project Server. Our team has provided all the specifics in our blog posting including a link to the complete Microsoft TechNet article. You can find all the information.