How do I have different conditions for Amazon and eBay (i.e. Used - Very Good and Used)

Amazon's used conditions are more specific than eBay's, it also has special collectable conditions which you must get approval for (here).

The error you often get is that selecting a special, specific condition is not recognized by eBay - but picking the generic, used condition shows up on Amazon as "Used - Acceptable."

Create a Custom User Field and map it to the JSON pointer /attributes/condition_type/0/value in Amazon field mappings. For help mapping Custom Fields to Amazon's SP-API feed, check out the SureDone Guide on How To: Use Amazon Field Mapping.

The acceptable values for this field (typed exactly as they appear) are:

• new
• used_like_new
• used_very_good
• used_good
• used_acceptable
• collectible_like_new
• collectible_very_good
• collectible_good
• collectible_acceptable
• refurbished
• club