Merge listing deals with the Product level whereas Link listing deals with the Variant level.
1. Merge listing on the Product page
This is the option you should use if you would like to merge two Products, with all of their Variants together.
2. Merge listing on the Variant page
This is the same as the Merge listing feature on the Product page. This is the option you should use if you would like to merge two Products, with all of their Variants together.
3. Link Market listing on the Variant page
Link Market Listing is the act of moving Market Listings to a new variant. This is the option you should use if you would like to link a variant to another variant. Sometimes, we import from multiple channels and create a variant based on SKU.
If you have the same product as two different variants on different marketplaces, that is, Variant1 has an Amazon and eBay listing and Variant2 has a Walmart and Shopify Listing, you can use Link Market listings to move the Market Listings from variant2 to variant1 so they are all in sync.
4. Merge button next to the market listing on the Product page
This means that more than one parent listing exists for this product on Amazon. You will need to merge these listings into 1 in order to sync your Product Catalog data to your listings.
Listing Mirror will delete your listings from the marketplace and then recreate them as one.
If you have any trouble with this, as always, reach out to Support!