68HC000 said:A scammer is someone who has cheated you out of your money and/or goods. Either you shipped the items and the scammer didn't pay, or they took your money but refuse to send the items you paid for.
A timewaster is someone who reassures a seller of a sale, then backs out. This can cause problems since a seller may take the item off the market and put it "on hold" for a timewaster, only for that person to back out causing the seller to miss other possible selling oportunities.