What many customers don’t realize is that one of the versions is more adapted for use within a corporate network (Power Pivot for Excel), while the other can work either inside a corporate network or in a cloud environment (Power Pivot for SharePoint).
Power Pivot for Excel is an add-in for Excel on a PC that provides great business intelligence around any data that can be directly accessed by that PC. Inside a corporate network, if a PC can directly access databases, then Power Pivot for Excel can “Crush the Numbers” as advertised. In a shared cloud environment, the only way for a PC to access databases over the Internet is using the OData protocol, which is typically 10 to 1,000 times slower than direct database access, so reports come up very slowly or not at all. In a private cloud environment with dedicated server(s), the situation is better. Power Pivot for Excel users can also access OLAP cube databases directly over the Internet from their PCs.
Power Pivot for SharePoint is branding terminology for the Enterprise version of SQL Server Analysis Services (SSAS) configured in SharePoint mode. Users of this version of Power Pivot can bring up interactive reports in SharePoint that pull real-time data directly (and quickly) from production or reporting databases. Power Pivot for SharePoint works equally well within corporate networks or private clouds, but since it requires dedicated servers and the Enterprise version of SQL Server, it is not available for shared clouds.
In our experience, most enterprise customers really want Power Pivot for SharePoint, but they sometimes get confused when a shared cloud provider says that they support Power Pivot. Customers don’t realize that the shared cloud provider is really saying, “if you install the Power Pivot add-on to Excel on your PC, then you can use that to evaluate data using the [relatively slow] OData protocol.” The only way to get the fast, flexible, real-time analysis capabilities of Power Pivot for SharePoint in a cloud-based solution is to get it from a private cloud.
More information about PowerPivot and other Business Intelligence tools available for SharePoint and Project Server private clouds can be found in this description of Custom Cloud BI packages.