What is your dimension breakdown? Product?
If there are multiple products in the same order, the total orders will be de-duplicated.
Example: If I go to your site and purchase "Item A", "Item B" and "Item C" in the same order, the report will look like:
Orders
1
Products
Item A 1
Item B 1
Item C 1
You wouldn't count this as "3" orders when all three products were purchased in the same order, with the same Order ID / Transaction ID... it's still one order.