UPDATE - Nov 2019
Amazon will be deprecating target_audience_keyword and subject_keyword.
The only keyword attribute that will be accepted from vendors will be Generic Keywords.
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We asked the folks over at Amazon to give us a little explanation for our users on the difference between Subject Keyword vs Target Audience Keyword vs Generic Keyword and which ones have the most impact on SEO ranking.
The first thing to know is that the target_audience_keyword and subject_keyword attributes are specific to product types and not used for all product types.
Subject_keyword are specific to media products. This attribute used by industry standards to describe subjects and genres of books, music, etc.
Target_audience_keyword are used to identify the user of a particular product.
Example: toys_and_games,home,bed,baby_product,tools,.etc
SEO ranking is derived by Amazon's internal algorithm and that keywords attributes have their own usage in website search.
"SEO Strategy" is also a separate initiative (and downstream) of our connection to Amazon or other ingestion channels like directly through Vendor Central. If you are enrolled in this separate initiative you will get this benefit.
We would suggest you reach out to your respective vendor manager (contacts who set you up in Amazon Vendor Central) to know more.
Keyword Types
Subject Keyword
This attribute represents values provided which will be used as hidden search terms.
Recommendation:
Provide keywords that describe the subject of the item, these are hidden terms used in search.
Generic Keyword
This attribute represents terms that may be relevant to customer searches.
Recommendation:
Provide any terms that may be relevant to customer searches.
Target Audience Keyword
This attribute represents the item's target audience.
Recommendation:
Provide a few terms that describe the type of end user this product was designed.