1a. Pivot Table can only accept a single source of data.
1b. Power Pivot Table can accept multiple sources of data.
2a. Pivot Table can only do simple summary such as Sum, Count, Max, Min
2b Power Pivot Table can do complex calculations
3a. Pivot table can only accept data from the entire source (worksheet)
3b Power Pivot Table let you pick choose the columns from source to be included in the report