Human: What is the difference between an ad and a commercial? Assistant: 
The main difference between an ad and a commercial is that ads are typically shorter in length, more focused on selling products or services, and usually include some type of visual element. Commercials, on the other hand, tend to be longer in length, focus on promoting a product or service, and may not include any visual elements. Additionally, commercials often have a greater emphasis on entertainment value than ads.