What is Simple/Variable or External/Affiliate ?
External/Affiliate is for use with Geo-Targeting, and you can learn more here: https://kb.imsuccesscenter.com/kb/aa-geo-targeting/ and here https://kb.imsuccesscenter.com/kb/aa-geo-targeting-persistent-external-affiliate-simple-variable-settings/
Simple/Variable is for use when you’re focusing on your own region or location. So, If I’m solely focused on Canada, I would set things to Simple/Variable. But, if I wanted to potentially sell to people in the US I would need to set things to External/Affiliate as in this explanation:
Geo Targeting Settings
Earn more commissions from international visitors by sending them to international versions of Amazon’s website.
To enable geo-targeting for a particular country, enter your Associate ID for that country in the box below.
When a visitor clicks a Buy Now button on your site, AzonAuthority will check the visitor’s country, check to see if the product also exists on the Amazon website for that visitor’s country and if so, redirect the visitor to the product page on their own country’s Amazon website.
If a visitor is from a non-geo-targeting-enabled country they will be sent to the country specified on the General tab.
If you choose United States (Amazon.com) as your default country on the General tab, add your Amazon United Kingdom (Amazon.co.uk) Associate ID below, and post a product, here’s what will happen.
If a visitor from the United Kingdom comes to your site and clicks the Buy link, AzonAuthority will check if the product is present on Amazon.co.uk. If so, the visitor will be sent to the product page on Amazon.co.uk.
If the visitor isn’t from the UK, or the same product isn’t present on Amazon.co.uk, the visitor will be sent to the product page on Amazon.com.