Analysis Services and Reporting Services can be installed as shared services in a SharePoint farm. Installing the services in a farm enables BI features that are only available in SharePoint. These features include PowerPivot for SharePoint and Power View, the new Reporting Services ad hoc interactive report designer that runs on PowerPivot or Analysis Services tabular data models.
PowerPivot for SharePoint is used for PowerPivot data access in a SharePoint farm. If you use PowerPivot for Excel to create PowerPivot workbooks, you can install PowerPivot for SharePoint as the data engine for those workbooks when you access them from a SharePoint library. Once you save a PowerPivot workbook to SharePoint, you can use it as a data source for Power View reports.