Sheriff auctions are court-ordered public sales of properties, usually as a result of a creditor or lender having instituted legal action in order to recover unpaid debt. The sale is conducted by a sheriff of the court, and the property is sold to the highest bidder. These auctions are usually advertised in local newspapers and are open to the public.
One of the main advantages of sheriff auctions is that they offer the opportunity to purchase properties at a lower cost because the properties can be difficult to view internally and they are usually only advertised in local newspapers, the government gazette and on Sheriff Listing websites like SheriffHQ.co.za.
On the other hand, bank repossessed properties for sale are properties that have bought by the bank or other financial institution at a Sheriff Auction. The bank or other lender will then try to sell the property at a higher price than it was sold for at the sheriff auction.
These properties are generally then sold through normal channels, such as through a real estate agent or on a property website. Viewing the property internally is usually easier than a Sheriff Auction property. For these reasons the prices of repossessed properties tend to be higher.
If you are looking for the best possible bargain you are much better off looking at a Sheriff Auction. See this article that goes into more depth on why sheriff auctions are way better than repossessed properties.