This article is in two sections:

1) Using your ecommerce platform to sync different images on eBay to those used on your website:

Magento 1.x

Add an image to the product and set the Label field to gallery. If you don't want to show it on the website then set it to 'Exclude'.

Magento 2.x

Add an image to the product and set the Alt Text field to gallery. If you don't want the image to appear on your site, tick the Hide from Product Page checkbox.

WooCommerce

It is not currently possible to add an eBay specific image in WooCommerce (WooCommerce limitation).

Shopify

It is not currently possible to add an eBay specific image in Shopify (Shopify limitation).

BigCommerce

It is not currently possible to add an eBay specific image in BigCommerce (BigCommerce limitation).

Ecwid

It is not currently possible to add an eBay specific image in Ecwid (Ecwid limitation).

2) Turn image sync off for eBay and manage images directly on eBay listings:

To do this:

1) Click Customize grid:

2) Scroll right and check 'Catalog Image Sync'

3) Return to the XpressGrid and scroll right on the grid to find the image sync column:

4) Toggle image image sync as required either on individual products or in bulk

OFF means eBay listing will NOT be updated from your ecommerce platform images i.e. you can change on eBay directly and it won't be overwritten. 

ON means images are being synced from your ecommerce platform to your eBay listings (any changes directly on eBay will be overwritten).