Minimum Advertised Price is the minimum Price allowed by the manufacturer of a Product that can be used by a seller when advertising a Product. It applies to the US only.
If you choose to set a Minimum Advertised Price, a buyer will get a discount equal to the difference between Minimum Advertised Price and Product Price.
None - Discounted Price will not be shown during either Pre-Checkout or Checkout. A buyer will be aware of discount before the payment is done.
During Checkout - Discounted Price will be shown on the eBay checkout flow page. A buyer will be aware of discount before the purchase is confirmed.
Pre-Checkout - the information of Discounted Price will be available on the product page. A buyer will be aware of discount before he decides to make a purchase by clicking "See Price" link. Discounted Price will be shown in a pop-up window.
When both Strike Through Price and Minimum Advertised Price are selected, only Minimum Advertised Price is sent to eBay. The Minimum Advertised Price should be lower than the Strike Through Price; if not, the Product will not be listed on eBay.