A quick view option in the Woo – Products widget shows the product details in a popup. This allows users to take a closer look at the product and its details without moving on to a new page.
When you enable a quick view on the image it will show the popup on the click of the image.
While when you enable a quick view on the button, it will add a Quick view badge to the product image and will show a popup on its click. Below is the example for the button option.
More customization options are available under the Style Tab -> Quick View section. (?)