What's the difference between product description and variant description? Where do I put my product description?

A product description is the part of the product listing that tells you what the product is and what it does.

A variant description tells you the details in terms of variables such as size, color.

To set a Product Description, click on Inventory and on the top right-hand corner of the page, select 'Create a New'. On the page, you will see a box called 'Product Description'.