Product Performance Report

The Product Performance report lets you see how your products performed from two different points of view:
You can get a good overview of which products were sold most, generated most revenue etc.
This report can be very helpful if you are trying to decide on what types of products to sell more of, which products to promote etc.

Here is an example for the Google Online Merchandise Store:

It looks like the insulated water bottle generated most revenue for the store during the month of August.

Note that the report shows unique purchases - this is the number of times this product was part of a transaction. If a user buys 2 products in one transaction, it would be only 1 unique purchase. As you can see in this report, the average quantity, which is the average number of this kind of product sold in one transaction is relatively high, so it looks like there are some purchases on this site that are for events, where people buy in larger quantities.

Sales Performance Report

The sales performance report is very similar to the product performance report, but in this case, the report focuses on the transactions, not the products. This report can help to understand the average transaction value and the number of products bought in a transaction.

Here is an example for the Google Online Merchandise Store