When creating products, there's a variety of different image types that can be used to display your products in different pages/sections. You can choose a single image to apply for all of them, or separate images for each. See the different types below:
The base image is the main image on the product detail page. Image zoom is activated if you upload an image that is larger image than the image container. Depending on the level of zoom that you want to achieve, the base image should be two or three times the size of the container. Example sizes: 470 x 470 pixels (without Zoom), 1100 x 1100 pixels (with Zoom)
The small image is used for the product images in listings on category and search results pages and to display the product images needed for sections such as for Up-sells, Cross-sells, and the New Products List. Example size: 240 x 240 pixels
A swatch can be used to illustrate the color, pattern, or texture in filters on category pages. Example size: 50 x 50 pixels.
Thumbnail images appear in the thumbnail gallery, shopping cart and in some blocks such as Related Items. Example size: 50 x 50 pixels