At its most basic level AffiliateWP allows you to set a global referral rate which all affiliates share. For integrations that support per-product referral rates, affiliates can earn different commissions based on which product/s are purchased. AffiliateWP also allows you to set referral rates on a per-affiliate level which will override any per-product referral rate.
Affiliate Product Rates expands this even further, allowing different per-product referral rates on a per-affiliate level.