Wholesale pricing is sometimes referred to as reseller pricing. This is what you could expect to sell your domain in a "quick sale" situation. Advantages is its usually no problem to find a buyer at this loser price and the transactions are generally quick and easy. You'll often see domains sold at wholesale on forums such as NamePros and in domain auctions.
Reail pricing, also known as as "End User" pricing, is a fair price that you could expect when you locate a willing buyer that has a need for your domain. The sales price is higher, but it may take time and effort to locate the perfect buyer and the transaction may require some additional hand-holding. Sometimes you get lucky and the buyer comes to you wanting to buy your domain at a premium. More often than not though you will have to seek out these potential buyers yourself.
You can make profits selling to either market of domain buyer, or both. Like Mark mentioned, almost all sales taking place on this and other forums fall into the reseller category.